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
Criticism of Hadith highly of Mutawatir: However, orthodox hadith scholars find non-mutawatir hadith adequate. "According to the majority of the ulama of the four Sunni schools, acting upon ahad is obligatory even if ahad fails to engender positive knowledge. Thus, in practical legal matters," but not in "matters of belief", "a preferable "zann" [meaning, speculative] "is sufficient as a basis of obligation." Ibn al-Salah ( (d. 643/1245), "one of the most distinguished traditionists of the muta'akhkhirun", argues (according to Farooq), that because mutawatir type hadith is rare, "for much of Islamic praxis, certainty of knowledge is neither feasible nor required. Rather, probable or