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 al-Kattānī. `Āʼishah bint `Abd al-Raḥmān said in the foreword of her edition of the "Introduction": His book about the sciences of hadith is the best known of his works without comparison, to the extent that it is sufficient to say, "the Book of Ibn al-Ṣalāḥ", the intent being understood due to its popularity and stature. With the previous scholars, its subject matter overcame it, thus being referred to as, "the Book of Ibn al-Ṣalāḥ about `Ulūm al-Ḥadīth" or as he referred to it in its opening pages, "the Book of Familiarity with the Types of `Ulūm al-Ḥadīth". It has become