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 well known as of late as: "Muqaddimah Ibn al-Ṣalāḥ fi `Ulūm al-Ḥadīth", "Ibn al-Ṣalāḥ's Introduction to the Sciences of Hadith". Nūr al-Dīn `Itr, in the introduction to his edition of the "Introduction", concluded that its actual name is either "ʻUlūm al-Ḥadīth" ("The Sciences of Hadith") or "Ma`rifah Anwā`i `Ilm al-Ḥadīth" ("Familiarity with the Types of the Science of Hadith"). This is based upon the author's own usage in his own introduction in addition to the usage of other scholars in the centuries after the authoring of the book. Similar to Bint `Abd al-Raḥmān, he acknowledged that the book is most