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
Hadith terminology in and of itself"with the same definition a "ṣaḥīḥ hadith" except that the competence of one of its narrators is less than complete; while a "hadith" that is "ḥasan ligharihi" ("ḥasan due to external factors") is determined to be "ḥasan" due to corroborating factors such as numerous chains of narration. He states that it is then comparable to a "ṣaḥīḥ hadith" in its religious authority. A "ḥasan hadith" may rise to the level of being "ṣaḥīḥ" if it is supported by numerous "isnād" (chains of narration); in this case that "hadith" would be "ḥasan lithatihi" (""ḥasan" in and of itself")