It is an agreed upon fact that Qur’an and Sunnah are the integral part of Islamic shariah, and the entire reliable and irrefutable sunnah is preserved in authentic ahadith. A hadith is composed of two parts: the matn (text) and the isnad (chain of reporters).
A highly reliable and trustworthy chain of narrators (isnad) is pre-requisite for the text (matan) to be acceptable. Imam al-Bukhari remained extremely cautious while describing a hadith.
 

Classification of ahadith.

Muhaddatheen have classified the ahadith into different categories based upon the criterion set by them. These classifications are as follows:

1 - Classification of hadith on the basis of reliability and memory of the reporters:

These are classified into for categories:
(i) Sahih (sound) (ii) Hasan (good) (iii) Da’if (weak) (iv)Maudu (fabricated)

Sahih (sound)

A sahih hadith has to have following five characteristics:
(i) Its chain of transmitters is continuous and there is no missing person in the chain of narrators.
(ii) The narrators are God-fearing, trustworthy in their religion with righteous conduct (adl).
(iii) The narrators are of very accurate and strong memory (dabt).
(iv) It is not an isolated (shadh) hadith.
(v) It has no hidden defect (mudallis)

Grading for a hadith to be sahih:
• those which are transmitted by both al- Bukhari and Muslim;
• those which are transmitted by al-Bukhari only;
• those which are transmitted by Muslim only;

those which are not found in the above two collections, but
• which agree with the requirements of both al-Bukhari and Muslim;
• which agree with the requirements of al- Bukhari only;
• which agree with the requirements of Muslim only; and
• those declared sahih by other traditionists.*
[*al-Tibi, al-Husain b. 'Abdullah, al-Khulasah fi Usul al-Hadith (ed. Subhi al-Samarra'i, Baghdad, 1391), p. 36.]

Hasan (Good)

It is that hadith which does not contain a reporter accused of lying, it is not shadh and the hadith has been reported through more than one sanad. As defined by Imam Tirmizi.

The Hasan hadith is that which has following charateristics:
(i) Its chain of transmitters is continuous and there is no missing person in the chain of narrators.
(ii) The narrators are God-fearing, trustworthy in their religion with righteous conduct (adl).
(iii) The narrators are comparatively less accurate but have a good memory (dabt).
(iv) It is not an isolated (shadh) hadith.
(v) It has no hidden defect (mudallis)

Both categories, the Sahih and Hasan are used as a proof and are to be acted upon*.
[*Sheikh Ibn Uthaimin. Fatawa Islamiyah, Vol. 7, pg. 162]

Example of Hasan hadith.
Imam Ahmad reported that Yahya Ibn Saeed told him saying that Bahz Ibn Hakim said that his father informed him on the authority of his grand father: I said to the Prophet: Messanger of Allah, whom should I be (specially) good ? The Prophet said,” to your mother”. This he repeated thrice. Then he said, “to your father, then to him who is near of kin, one after the other”.

This hadith qualifies all the characteristics of a sahih hadith except that one of the hadith compilers has pointed out slight weakness in the dabt (memory0 of Bahz Ibn Hakim. However his father Hakim has been declared trustworthy by critics like Ibn Hibban and Imam Nasai.

Daif (weak).
A daif (weak) hadith is that in which;
(i) There is a discontinuity in the chain of narrators (isnad).
(ii) One of the reporter has a disparaged character and does not posses the ability of retaining the text.
(iii) There is ambiguity in the isnad or in the matan of hadith
(iv) The hadith is shaaz or mu'alall.

The daif hadith is further classified into different categories depending upon the defects in the qualification of isnad, these are;
i )Mursal ii) Mu’allaq iii) Mudallas iv) Munqati’ and v) Mu’dal

These will be defined at another suitable place.

The lesser the number and importance of defects, lesser the hadith is weak. More the number and severity of defects, more the hadith is maudu (fabricated)

Maudu’ (fabricated)
Imam Al-Dahabi defines a maudu’ hadith is that in which;
(i) The matan (text) is against the established norms of Prophet’s sws sayings, and
(ii) Its one or more reporters are liars.

Al-Nawqwi in his ‘Taqrib’ writes that Maudu' ahadith are also recognised by external evidence related to a discrepancy found in the dates or times of a particular incident. For example, Ibn al-Qayyim, in ‘al-Manar al-Munif fi 'l- Sahih wa 'l-Da'if’ mentioned that when the second caliph, 'Umar b. al- Khattab decided to expel the Jews from Khaibar, some Jewish dignitaries brought a document to 'Umar apparently proving that the Prophet sws had intended that they stay there by exempting them from the jizyah (tax on non-Muslims under the rule of Muslims); the document carried the witness of two Companions, Sa'd b. Mu'adh and Mu'awiyah b. Abi Sufyan. 'Umar rejected the document outright, knowing that it was fabricated because the conquest of Khaibar took place in 6 AH, whereas Sa'd b. Mu'adh died in 3 AH just after the Battle of the Trench, and Mu'awiyah embraced Islam in 8 AH, after the conquest of Makkah!

A few examples of maudu’ (fabricated) ahadith:
1. Allah says, "I was a hidden treasure, and I wished to be known, so I created a creation (mankind), then made Myself known to them, and they recognised Me."
2. "He who knows himself, knows his Lord."
3. "Love of one's homeland is part of Faith."
4. "Seek knowledge, even if you have to go to China."
5. "The ink of the scholar is holier than the blood of the martyr."
2 - Classification of hadith on the basis of the reference to a particular authority:
Such hadith can be classified into four categories; i) Qudsi ii) Marfu’ iii) Mauquf iv) Maqtu’

Qudsi.
Hadith Qudsi is that in which the words used are that of Prophetsws but the meanings are from Allah swt. The hadith Qudsi is brought down to Prophet sws through revelations and during sleep.

Example hadith Qudsi
i) Narrated / Authority Of: Abu Huraira
who said that the Messenger of Allah (peace and blessings of Allah be upon him) said: "When Allah decreed the Creation He pledged Himself by writing in His book which is laid down with Him: 'My mercy prevails over my wrath.'" It was related by Muslim (also by al-Bukhari, an-Nasa'i and Ibn Majah).

ii) Narrated / Authority of : Abdullah ibn Abbas
Who said that the Messenger of Allah (peace be upon him), said Allah said:: "He has written down the good deeds and the bad ones. Then He explained it [by saying that] he who has intended a good deed and has not done it, Allah writes it down with Himself as a full good deed, but if he has intended it and has done it, Allah writes it down with Himself as from ten good deeds to seven hundred times, or many times over. But if he has intended a bad deed and has not done it, Allah writes it down with Himself as a full good deed, but if he has intended it and has done it, Allah writes it down as one bad deed."

iii) Narrated / Authority Of: Abu Huraira
who said that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Allah said: 'Sons of Adam inveigh against [the misfortunes of] Time, and I am Time, in My hand is the night and the day.' " It was related by al-Bukhari (also by Muslim).

Difference between the Qura’n and Hadith Qudsi (Both being words of Allah):

• Qura’n is a miracle whereas hadith Qudsi is not.
• Quran has been revealed upon the Prophet sws through a medium – the Gabriel, whereas Hadit Qudsi is revealed directly upon the Prophet sws, without medium.
• In Qura’n both the words and their meanings are from Allah swt whereas in hadith Qudsi the words used may be from the Prophet sws or Allah swt, whereas the meaning are always from Allah swt.
• The munkir (detestable ) of Qura’n is a kafir, but a munkir of hadith Qudsi is not kafir but a condemned one.
• It is desirable to have ablution before reading Qura’n whereas this is not the case with hadith Qudsi.

Marfu (Elevated)
A marfu (elevated) hadith is that which is transmitted through a chain of narrators that ultimately reaches to the Prophet sws.

Example of marfu hadith.
Imam Bukhari reported from Al-Humaidi Abdullah Ibn Zubair who reported from Sufyan who reported from Yahya b. Sa'id al-Ansari who reported from Muhammad b. Ibrahim al-Taymi who reported from 'Alqamah b. Waqqas al-Laithi, who said: I heard 'Umar b. al- Khattab saying, while on the pulpit, "I heard Allah's Messenger (may Allah bless him and grant him peace) saying: The reward of deeds depends on the intentions, and every person will get the reward according to what he has intended; so whoever emigrated for wordly benefits or for a woman to marry, his emigration was for what he migrated."

Mauquf (stopped)
A mauquf (stopped) hadith is that which stops at one of the sahaba (companions) and is not traced back to the Prophet sws.

Example of mauquf hadith.
Abu Bakr, Ibn Abbas and Ibn Zubair narrated, “"The grandfather is (treated like) a father."( Sahih Bukhari, Kitab al-fara’id)
It should be noted that certain expressions used by a Companion generally render a hadith to be considered as being effectively marfu' although it is mauquf on the face of it, e.g. the following:

"We were commanded to ..."
"We were forbidden from ..."
"We used to do ..."
"We used to say/do ... while the Messenger of Allah was amongst us."
"We did not use to mind such-and-such..."
"It used to be said ..."
"It is from the Sunnah to ..."
"It was revealed in the following circumstances: ...", speaking about a verse of the Qur'an.

Maqtu (severed)
A maqtu (severed) hadith is that in which is narrated by a successor.

Example of maqtu hadith.
Muslim reports in the Introduction to his Sahih that Ibn Sirin (d. 110) said, "This knowledge (i.e. Hadith) is the Religion, so be careful from whom you take your religion."

Imam Malik's Al-Muwatta', one of the early collections of hadith, contains a relatively even ratio of these types of hadith, as well as mursal ahadith (which are discussed later). According to Abu Bakr al-Abhari (d. 375), Al- Muwatta' contains 600 marfu' ahadith, 613 mauquf ahadith, 285 maqtu' ahadith, and 228 mursal ahadith; a total of 1726 ahadith.

3 - The classification of hadith on the basis of the links in the isnad.
Such hadith may be classified as; i) Musnad ii) Muttasil iii) Mursal iv) Munqati

v) Mu’adal vi) Mu’allaq

Musnad(supported)
Al-Hakim in his book ‘ Ma’rifah Ulum al-hadith’ defines a musnad ("supported") hadith as follows: "A hadith which a traditionalist reports from his shaikh (teacher) from whom he is known to have heard (ahadith) at a time of life suitable for learning, and similarly in turn for each shaikh, until the isnad reaches a well- known assahabi (Companion), who in turn reports from the Prophet sws”.

The term musnad is also applied to those collections of ahadith which give the ahadith of each assahabi (companion) separately. Among the early compilers of such a Musnad were Yahya b. 'Abd al- Hamid al-Himmani (d. 228) at Kufah and Musaddad b. Musarhad (d. 228) at Basrah. The largest existing collection of ahadith of Companions arranged in this manner is that of Imam Ahmad b. Hanbal (d. 241), which contains around 30,000 ahadith. Another larger work is attributed to the famous Andalusian traditionalist Baqi b. Makhlad al-Qurtubi (d. 276), but unfortunately it is now untraceable.
Muttasil (continuous).

A muttasil hadith is that which has an uninterrupted isnad and goes back only to a companion or successor.
Mursal (hurried).

A mursal hadith is that in which the link between the successor and the Prophet(P) is missing, e.g., when a successor says "The Prophet said...".

Munqati`(broken).

A munqat’i hadith is that in which link anywhere before the successor (i.e., closer to the traditionalist recording the hadith) is missing.

Mu`adal (perplexing).

A mu’adal hadith in which reporter omits two or more consecutive reporters in the isnad.

Mu`allaq (hanging).

A mu’allaq hadith is that in which reporter omits the whole isnad and quotes the Prophet sws directly (i.e., the link is missing at the beginning).
4 - The classification of hadith on the basis of reporters involved in each stage of the isnad.
There are two types of such viz; hadith; i) mutawatir and ii) ahad. The ahad hadith is further classified into three groups; a) gharib b) aziz and iii) mushoor.

Mutawatir (consecutive)
A mutawatir hadith is that which is reported by such a large number of people that they cannot be expected to agree upon a lie, all of them together.
Al-Ghazali (d. 505) stipulates that a mutawatir narration be known by the sizeable number of its reporters equally in the beginning, in the middle and at the end.

Examples of mutawatir practices are the five daily prayers, fasting, zakat, the Hajj and recitation of the Qur'an. Among the verbal mutawatir ahadith, the following has been reported by at least sixty-two Companions from the Prophet (may Allah bless him and grant him peace), and has been widely-known amongst the Muslims throughout the ages: "Whoever invents a lie and attributes it to me intentionally, let him prepare his seat in the Fire."
Ahadith related to the description of the Haud Kauthar (the Basin of Abundant Goodness) in the Hereafter, raising the hands at certain postures during prayer, rubbing wet hands on the leather socks during ablution, revelation of the Qur'an in seven modes, and the prohibition of every intoxicant are further examples of verbal mutawatir ahadith.

Ahad (single)
A an ahad hadith or khabar wahid is one which is narrated by people whose number does not reach that of the mutawatir case. Ahad is further classified into: gharib, aziz and mushhur.

Gharib (scarce, strange)
A gharib hadith is that in which a single reporter is found relating it at some stage of the isnad.
Example of gharib hadith.

The saying of the Prophet sws, "Travel is a piece of punishment" is gharib; the isnad of this hadith contains only one reporter in each stage: Malik --- Yahya b. Abi Salih --- Abu Hurairah --- the Prophet (may Allah bless him and grant him peace). With regard to its isnad, this hadith is sahih, although most gharib ahadith are weak; Ahmad b. Hanbal said, "Do not write these gharib ahadith because they are unacceptable, and most of them are weak."

Aziz (rare, strong)
It is that hadith in which at any stage in the isnad, only two reporters are found to narrate the hadith.
For example, Anas ra reported that the Messenger of Allah (may Allah bless him and grant him peace) said, "None of you (truly) believes until I become more beloved to him than his father, his son, and all the people."
Two reporters, Qatadah and 'Abdul 'Aziz b. Shu'aib, report this hadith from Anas, and two more reporters narrate from each of them: Shu'bah and Sa'id report from Qatada, and Isma'il b. Ulayyah and 'Abd al-Warith from 'Abd al-'Aziz; then a group of people report from each of them.

Mashhur (famous)
A mashhur hadith is that which is reported by more than two reporters. According to some scholars, every narrative which comes to be known widely, whether or not it has an authentic origin, is called mashhur.

According to al-'Ala'i (Abu Sa'id Khalil Salah al-Din, d. 761), a hadith may be known as aziz and mashhur at the same time. By this he means a hadith which is left with only two reporters in its isnad at any stage while it enjoys a host of reporters in other stages, such as the saying of the Prophet (may Allah bless him and grant him peace), "We are the last but (will be) the foremost on the Day of Resurrection." This hadith is aziz in its first stage, as it is reported by Hudhaifah b. al-Yaman and Abu Hurairah only. It later becomes mashhur as seven people report it from Abu Hurairah.
5 - The classification of hadith on the basis of the manner in which the hadith is reported.
Such hadith may be classified into i) Mudallas and ii) Musalsal

Mudallas (concealed)
The mudallas hadith is that in which a reporter conceals (tadlis) the identity of his shaikh (teacher) in such a manner that the concealment is not apparent.

Tadlis.
Tadlis means to hide some defects. Tadlis is the word derived from ‘da-la-sa’ meaning ‘zulmat’ or darkness. In the science of hadith, ‘tadlis’ means the practice in which a reporter hides the identity of his shaikh.

Ibn al-Salah describes two types of tadlis:
1. tadlis al-isnad. A person reports from such a reporter to whom he met, but there is no proof that he listened that hadith from that person.Or reports from such a contemporary person to whom he did not met but pretends that he heard the hadith from him in person. A mudallis (one who practises tadlis) here usually uses the mode ("on the authority of") or ("he said") to conceal the truth about the isnad.
2. tadlis al-shuyukh. The reporter does mention his shaikh by name, but uses a less well-known name, by-name, nickname etc., in order to conceal his shaikh's identity.
Al-'Iraqi (d. 806), in his notes on Muqaddimah Ibn al-Salah, adds a third type of tadlis:
3. tadlis al-taswiyyah. To explain it, let us assume an isnad which contains a trustworthy shaikh reporting from a weak authority, who in turn reports from another trustworthy shaikh. Now, the reporter of this isnad omits the intermediate weak authority, leaving it apparently consisting of reliable authorities. He plainly shows that he heard it from his shaikh but he uses the mode "on the authority of" to link his immediate shaikh with the next trustworthy one. To an average student, this isnad seems free of any doubt or discrepancy. This is known to have been practised by Baqiyyah b. al-Walid, Walid b. Muslim, al-A'mash and al- Thauri. It is said to be the worst among the three kinds of tadlis.
Musalsal (uniformly-linked)
A musalsal hadith is that in which all the reporters use the same mode of transmission such as 'an, haddathana (he said to us), etc., repeat any other additional statement or remark, or act in a particular manner while narrating the hadith. Knowledge of musalsal helps in discounting the possibility of tadlis.
6 - The classification of hadith on the basis of the nature of the text and isnad

Such hadith may be classified as; i) Shadhdh ii) Munkar and iii) Mudraj

Shadhdh (rare)

A shadhdh hadith is that which is reported by a trustworthy person but goes against the narration of a person more reliable and trustworthy than him.

Shadhdh hadith is of two types.

Shadhdh al- Sanad: It is that hadith in which there is rarity (shudhdh) in the sanad.

Shadhdh al-Matan: It is that hadith in which there is rarity (shudhdh) in the matan (text).

Munkar (denounced)
A munkar hadith is that in which a narration goes against another authentic hadith reported by a weak narrator as defined by Ibn Hajar.
Ahmad Ibn Hanbal says, any hadith reported by a weak narrator is munkar.
Ibn Kathir quotes the following two ahadith in his Tafsir, the first of which is acceptable, whereas the second contradicts it and is unreliable:
1. Ahmad === Abu Mu'awiyah === Hisham b. 'Urwah --- Fatimah bint al-Mundhir --- Asma' bint Abi Bakr, who said, "My mother came (to Madinah) during the treaty Quraish had made, while she was still a polytheist. So I came to the Prophet (may Allah bless him and grant him peace) and said to him, 'O Messenger of Allah, my mother has come willingly: should I treat her with kindness?' He replied, 'Yes! Treat her with kindness'."
2. Al-Bazzar === 'Abdullah b. Shabib === Abu Bakr b. Abi Shaibah === Abu Qatadah al- 'Adawi --- the nephew of al-Zuhri --- al- Zuhri --- 'Urwah --- 'A'ishah and Asma', both of whom said, "Our mother came to us in Madinah while she was a polytheist, during the peace treaty between the Quraish and the Messenger of Allah (may Allah bless him and grant him peace). So we said, 'O Messenger of Allah, our mother has come to Madinah willingly: do we treat her kindly?' He said, 'Yes! Treat her kindly'."

Ibn Kathir then remarks:
"This (latter) hadith, to our knowledge is reported only through this route of al- Zuhri --- 'Urwah --- 'A'ishah. It is a munkar hadith with this text because the mother of 'A'ishah is Umm Ruman, who was already a Muslim emigrant, while the mother of Asma' was another woman, as mentioned by name in other ahadith."
In contrast to a munkar hadith, if a reliable reporter is found to add something which is not narrated by other authentic sources, the addition is accepted as long as it does not contradict them; and is known as ziyadatu thiqah (an addition by one trustworthy).
Example of munkar.
An example is the hadith of al-Bukhari and Muslim on the authority of Ibn Mas'ud: "I asked the Messenger of Allah (may Allah bless him and grant him peace), 'Which action is the most virtuous?' He said, 'The Prayer at its due time'." Two reporters, Al-Hasan b. Makdam and Bindar, reported it with the addition, "... at the beginning of its time"; both Al-Hakim and Ibn Hibban declared this addition to be sahih.
Mudraj (interpolated)
A mudraj hadith is that in which there is an addition in the matan(text) or in isnad which was not present initially. Mudraj is the word derived from ‘idraj’ meaning interpolation.
Mudraj hadith is further classified into i) Mundraj al-matan – in which the addition is in text, and ii) Mundraj al-isnad – in which addition is in isnad .
Example of mundraj.
Al-Khatib relates via Abu Qattan and Shababah who heard from--- Shu'bah --- Muhammad b. Ziyad who heard from --- Abu Hurairah who heard from --- The Prophet sws who said,
"Perform the ablution fully; woe to the heels from the Fire!"
Al-Khatib then remarks,
"The statement, 'Perform the ablution fully' is made by Abu Hurairah, while the statement afterwards, 'Woe to the heels from the Fire!', is that of the Prophet sws. The distinction between the two is understood from the narration of al- Bukhari, who transmits the same hadith and quotes Abu Hurairah as saying, "Complete the ablution, for Abu 'l-Qasim sws who said: Woe to the heels from the Fire!"."
Such an addition may be found in the beginning, in the middle, or at the end, A reporter found to be in the habit of intentional idraj is generally unacceptable and considered a liar. However, the traditionists are more lenient towards those reporters who may do so forgetfully or in order to explain a difficult word.
7 - The classification on the basis of hidden defect found in the text or isnad of a hadith.

Such hadith is categirised into; i) Maqlub ii) Mudtarib and Ma’lul or Ma’uallal
Maqlub (changed, reversed)
A maqlub hadith is that in which the name of a reporter is replaced by another one in isnad or the order of the text is reversed. Maqlub hadith is further classified into; i) Maqlub al-Sanad and ii) Maqlub al-Matan.

Maqlub al-Sanad.
In such hadith in which the name of a reporter is replaced by another one.
For example, quoting Abu Hurairah as the reporter from the Prophet sws although the actual reporter was someone else, or by reversal of the name of the reporter, e.g. mentioning Walid b. Muslim instead of Muslim b. Walid, or Ka'b b. Murrah instead of Murrah b. Ka'b.
The famous trial of al-Bukhari by the scholars of Baghdad provides a good example of a maqlub isnad. The traditionists, in order to test their visitor, al-Bukhari, appointed ten men, each with ten ahadith. Now, each hadith (text) of these ten people was prefixed with the isnad of another. Imam al-Bukhari listened to each of the ten men as they narrated their ahadith and denied the correctness of every hadith. When they had finished narrating these ahadith, he addressed each person in turn and recounted to him each of his ahadith with its correct isnad. This trial earned him great honour among the scholars of Baghdad.

Maqlub al Matan.
In this hadith the order of the sentences of a narration is changed or reversed.
For example, in his transmission of the famous hadith describing the seven who will be under the shelter of Allah on the Day of Judgment, Muslim reports one of the categories as, "a man who conceals his act of charity to such an extent that his right hand does not know what his left hand gives in charity." This sentence has clearly been reversed by a reporter, because the correct wording is recorded in other narrations of both al-Bukhari and Muslim as follows: "... that his left hand does not know what his right hand gives ..."
Mudtarib (shaky)
A mudtarib hadith as described by Ibn Kathir is that in which, if reporters disagree about a particular shaikh, or about some other points in the isnad or the text, in such a way that none of the opinions can be preferred over the others, and thus there is uncertainty about the isnad or text. Such hadith are further classified as; i) Mudtarib al-Sanad and ii) Mutarib al-Matan.
For example with regard to idtirab in the isnad, it is reported on the authority of Abu Bakr that he said, "O Messenger of Allah! I see you getting older?" He (may Allah bless him and grant him peace) replied, "What made me old are Surah Hud and its sister surahs." Al-Daraqutni says,
"This is an example of a mudtarib hadith. It is reported through Abu Ishaq, but as many as ten different opinions are held about this isnad: some report it as mursal, others as muttasil; some take it as musnad of Abu Bakr, others as musnad of Sa'd or 'A'ishah. Since all these reports are comparable in weight, it is difficult to prefer one above another. Hence, the hadith is termed as mudtarib, as reported by ibn Kathir in his book ‘Ikhtisar’.
As an example of idtirab in the text, Rafi' b. Khadij said that the Messenger of Allah sws forbade the renting of land. The reporters narrating from Rafi' give different statements, as follows:
1. Hanzalah asked Rafi', "What about renting for gold and silver?" He replied, "It does not matter if it is rent for gold and silver."
2. Rifa'ah --- Rafi' --- the Prophet (may Allah bless him and grant him peace), who said, "Whoever owns a piece of land should cultivate it, give it to his brother to cultivate, or abandon it."
3. Salim --- Rafi' --- his two uncles --- the Prophet (may Allah bless him and grant him peace), who forbade the renting of farming land.
4. The son of Rafi' --- Rafi' --- the Prophet (may Allah bless him and grant him peace), who forbade the renting of land.
5. A different narration by Rafi' from the Prophet (may Allah bless him and grant him peace), who said, "Whoever owns a piece of land should either cultivate it or give it to his brother to cultivate. He must not rent it for a third or a quarter of the produce, nor for a given quantity of the produce."
6. Zaid b. Thabit said, "May Allah forgive Rafi'! I am more aware of the hadith than he; what happened was that two of the Ansar (Helpers) had a dispute, so they came to the Prophet (may Allah bless him and grant him peace), who said after listening to their cases, 'If this is your position, then do not rent the farms.' Rafi' has only heard the last phrase, i.e., 'Do not rent the farms'."
Because of these various versions, Ahmad b. Hanbal said,
"The ahadith reported by Rafi' about the renting of land are mudtarib. They are not to be accepted, especially when they go against the well-established hadith of Ibn 'Umar that the Messenger of Allah (may Allah bless him and grant him peace) gave the land of Khaibar to the Jews on condition that they work on it and take half of the produce."

Ma'lul or Mu'allal (defective)
A ma'lul (defective) hadith is one which appears to be sound, but thorough research reveals a disparaging factor, as described by Ibn al-Salah. Such factors can be:
1. declaring a hadith musnad when it is in fact mursal, or marfu' when it is in fact mauquf;
2. showing a reporter to narrate from his shaikh when in fact he did not meet the latter; or attributing a hadith to one Companion when it in fact comes through another.

Ibn al-Madini (d. 324) says that such a defect can only be revealed if all the isnads of a particular hadith are collated. In his book al- 'Ilal, he gives thirty-four Successors and the names of those Companions from whom each of them heard ahadith directly. For example, he says that al-Hasan al-Basri (d. 110, aged 88) did not see 'Ali (d. 40), although he adds that there is a slight possibility that he may have seen him during his childhood in Madinah. Such information is very important, since for example, many Sufi traditions go back to al- Hasan al-Basri, who is claimed to report directly from 'Ali.

Being a very delicate branch of Mustalah al- Hadith, only a few well-known traditionists such as Ibn al-Madini (d. 234), Ibn Abi Hatim al-Razi (d. 327), al-Khallal (d. 311) and al-Daraqutni (d. 385), have compiled books about it. Ibn Abi Hatim, in his Kitab al-'Ilal, has given 2840 examples of ma'lul ahadith about a range of topics.

An example of a ma'lul hadith is one transmitted by Muslim on the authority of Abu Hurairah, who reports the Prophet (may Allah bless him and grant him peace) as saying,

"Allah created the land on Saturday; He created the mountains on Sunday; He created the trees on Monday; He created the things entailing labour on Tuesday; He created the light (or fish) on Wednesday; He scattered the beasts in it (the earth) on Thursday; and He created Adam after the afternoon of Friday, the last creation at the last hour of the hours of Friday, between the afternoon and night."
Regarding it, Ibn Taimiyyah says,

"Men more knowledgeable than Muslim, such as al-Bukhari and Yahya b. Ma'in, have criticised it. Al-Bukhari said, 'This saying is not that of the Prophet (may Allah bless him and grant him peace), but one of Ka'b al-Ahbar'."

Reference:
1- Khalid Mahmood Shaikh, Hadith and its Literary Style, National Book Foundation, Islamabad, Pakistan
2- Syed Abdul Majid Ghori, Syed Ahmad Zakaria Ghori, Uloom ul-hadith, Zamzam Publishers, Karachi, Pakistan
3- Prof.Abdul Rauf Zafar, Al-Tahdith fi Uloom al-hadith, Maktaba e Duddusia, Lahore, Pakistan
4- Muhammad Idrees Zubair, Hadith e Rasul, an introduction, Al-Masud Publications, Pakistan
5- Syed Manazir Hussain Gailani, Tadveen e Hadith, Maktaba al ilm, Lahore, Pakistan
6- Syed, Manzoor Noamani, Ma’aruf ul Hadith, Darul Isha’at, Karachi, Pakistan
7- Syed Suhyb Hasan, An Introduction to Science of Hadith, internet.
8- Islami Encylopedia, Al-Faisal Publications, Karachi, Pakistan