ḥadīth that have been accepted by every Muslim generation down from the time of the Holy Prophet.61 The mutawātir ḥadīth are accepted without criticizing their narrators. All others are called aḥād (pl. of aḥad or wāḥid meaning one, i.e., isolated).

The aḥād ḥadīth are divided into three classes, mashhūr (lit. well-known), technically ḥadīth which are reported through more than two channels at every stage; ‘azīz (lit. strong), that is, ḥadīth that are not reported through less than two channels; and gharīb (lit. strange or unfamiliar), namely ḥadīth in whose link of narrators there is only a single person at any stage. It should be noted that in this classification the condition as to the ḥadīth being narrated by more than two, or two, or less than two persons at any stage applies only to the three generations following the Companions of the Holy Prophet.

Of the two chief classes of ḥadīth, the mutawātir and the aḥād, the first are all accepted so far as the line of transmission is concerned, but the latter are further sub-divided into two classes, maqbūl or those which may be accepted, and mardūd or those which may be rejected. Those that are maqbūl, or acceptable, are again subdivided into two classes, ṣaḥīḥ (lit. sound), and ḥasan (lit. fair). The condition for a ḥadīth being ṣaḥīḥ or sound is that its narrators are ‘adl (men whose sayings and decisions are approved or whom desire does not deviate from the right course), and tāmm al-dzabṭ (guarding or taking care of ḥadīth effectually); that it is muttaṣil al-sanad, i.e., that the authorities narrating it should be in contact with each other, so that there is no break in the transmission; that it is ghair mu‘allal i.e., that there is no ‘illah or defect in it; and that it is not shādhdh (lit. a thing apart from the general mass) i.e., against the general trend of Ḥadīth or at variance with the overwhelming evidence of others. A ḥadīth that falls short of this high standard, and fulfils the other conditions but does not fulfil the condition of its narrators being tāmm al-dzabṭ (guarding or taking care of ḥadīth effectually), is called ḥasan (fair). Such a ḥadīth is regarded sound (ṣaḥīḥ) when the deficiency of effectual guarding is made up for by the large number of its transmitters. A sound ḥadīth is accepted unless there is stronger testimony to rebut what is stated therein. It has already been said that it is recognized by the collectors that a ḥadīth may be unacceptable either because of some defect in