Criticism of Hadith thus provides "certainty of knowledge" of what Muhammad said, in fact it is only the much rarer subset of sahih -- "mutawatir" hadith -- that provide certain knowledge. "Mutawatir" means the report "of a large number of narrators whose agreement upon a lie is inconceivable. This condition must be met in the entire chain from the origin of the report to the very end." However, according to Wael Hallaq, "the bulk of hadith with which the traditionists dealt, and on the basis of which the Jurists derived the law" were known as "ahad" — i.e. non-"mutawatir" hadith; Hadith without "textually
Introduction to the Science of Hadith clarify that term and not necessarily establish it. He also distinguished his book by responding to the positions of other scholars in a detailed manner. Ibn al-Ṣalāḥ mentioned in his introduction to the "Introduction" 65 chapters, each specific to a particular type or term of hadith terminology before saying that an even larger number was conceivable. He began by discussing "ṣaḥīḥ" (authentic) as the first category, and then "ḥasan" (good) as the second, "ḍa`īf" (weak) the third, "musnad" (supported) the fourth and so on. Ibn Jamāʻah, in his abridgement, divided these terms into four different categories according to subject (and