The above-mentioned classification of ahadith plays a vital role in ascertaining the authenticity of a particular narration. Ibn al- Salah mentions sixty-five terms in his book, of which twenty-three have been discussed above. Two further types not included by Ibn al-Salah, mu'allaq and mutawatir, have been dealt with from other sources. The remaining forty-two types follow in brief, which help further distinguish between different types of narrations.

1. Knowledge of i'tibar ("consideration"), mutaba'ah ("follow-up") and shawahid ("witnesses"). Traditionists are always in search of strengthening support for a hadith which is reported by one source only; such research is termed i'tibar. If a supporting narration is not found for a particular hadith, it is declared as fard mutlaq (absolutely singular) or gharib. For example, if a hadith is reported through the following isnad: Hammad b. Salamah - -- Ayyub --- Ibn Sirin --- Abu Hurairah --- the Prophet (may Allah bless him and grant him peace), research would be done to ascertain whether another trustworthy reporter has narrated it from Ayyub; if so, it will be called mutaba'ah tammah (full follow-up); if not, a reporter other than Ayyub narrating from Ibn Sirin would be sought: if so, it will be called mutaba'ah qasirah (incomplete follow-up). Whereas mutaba'ah applies to the isnad, i.e. other narrations from the same reporters, a narration which supports the text (meaning) of the original hadith, although it may be through a completely different isnad, is called a shahid ("witness").85.

2. Afrad (singular narrations).

3. The type of character required in an acceptable reporter.

4. The way a hadith is heard, and the different ways of acquiring ahadith.

5. How a hadith is written, and punctuation marks used.

6. The way a hadith is reported.

7. The manners required in traditionists.

8. The manners required in students of Hadith.

9. Knowledge of a higher or lower isnad (i.e. one with less or more reporters respectively).

10. Knowledge of difficult words.

11. Knowledge of abrogated ahadith.

12. Knowledge of altered words in a text or isnad.

13. Knowledge of contradictory ahadith.

14. Knowledge of additions made to an isnad (i.e. by an inserting the name of an additional reporter).

15. Knowledge of a well-concealed type of mursal hadith.

16. Knowledge of the Companions.

17. Knowledge of the Successors.

18. Knowledge of elders reporting from younger reporters.

19. Knowledge of reporters similar in age reporting from each other.

20. Knowledge of brothers and sisters among reporters.

21. Knowledge of fathers reporting from their sons.

22. Knowledge of sons reporting from their fathers.

23. Knowledge of cases where e.g. two reporters report from the same authority, one in his early life and the other in his old age; in such cases the dates of death of the two reporters will be of significance.

24. Knowledge of such authorities from whom only one person reported.

25. Knowledge of such reporters who are known by a number of names and titles.

26. Knowledge of unique names amongst the Companions in particular and the reporters in general.

27. Knowledge of names and by-names (kunyah).

28. Knowledge of by-names for reporters known by their names only.

29. Knowledge of nicknames (alqab) of the traditionists.

30. Knowledge of mu'talif and mukhtalif (names written similarly but pronounced differently), e.g. Kuraiz and Kariz.

31. Knowledge of muttafiq and muftariq (similar names but different identities), e.g. "Hanafi": there are two reporters who are called by this name; one because of his tribe Banu Hanifah; the other because of his attribution to a particular Madhhab (school of thought in jurisprudence).

32. Names covering both the previous types.

33. Names looking similar but they differ because of the difference in their father's names, e.g. Yazid b. al-Aswad and al-Aswad b. Yazid.

34. Names attributed to other than their fathers, e.g. Isma'il b. Umayyah; in this case Umayyah is the mother's name.

35. Knowledge of such titles which have a meaning different from what they seem to be, e.g. Abu Mas'ud al-Badri, not because he witnessed the battle of Badr but because he came to live there; Mu'awiyah b. 'Abdul Karim al- Dall ("the one going astray"), not because of his beliefs but because he lost his way while travelling to Makkah; and 'Abdullah b. Muhammad al-Da'if ("the weak"), not because of his reliability in Hadith, but due to a weak physique.

36. Knowledge of ambiguous reporters by finding out their names.

37. Knowledge of the dates of birth and death of reporters.

38. Knowledge of trustworthy and weak reporters.

39. Knowledge of trustworthy reporters who became confused in their old age.

40. Knowledge of contemporaries in a certain period.

41. Knowledge of free slaves (mawali) amongst the reporters.

42. Knowledge of the homelands and home towns of reporters.86