Hadith of the Quran and Sunnah authenticity. The Shi'a claim that this hadith is the most authentic of hadiths, claiming that it has been narrated by over 35 companions of Muhammad. The "Hadith al-Thaqalayn" is used by the Shi'a, among other reasons, to support their belief of Ali's succession to Muhammad. Shi'as view this hadith as a clear indication that Muhammad wished to keep the matter of leadership within his own family, starting with his cousin Ali. They believe that Muhammad was clearly indicating that only the "Ahl al-Bayt" have a right to authority and leadership. It is based on this claim that the Shi'as reject
Introduction to the Science of Hadith al-Ṣalāḥ, in his "Introduction", codified the terminology established by those scholars before him based upon his reading of their works. He did so by citing some of those scholarly statements in the earlier works and deducing from them common terms and definitions in the manner of a scholar authoring a book of "fiqh" (jurisprudence). In this manner, his book was based upon those principles established by the earlier hadith specialists combined with some elements of "fiqh". An example of this would be the inclusion of the division of hadith into "mutawātir" and "āḥād". He therefore only mentioned the statements of