Hadith of the Quran and Sunnah al-Thaqalayn" multiple times in multiple settings in multiple wordings. They argue that Muhammad said "Hadith al-Thaqalayn" at Mount Arafat during his Farewell Sermon, at Ghadir Khumm, in the mosque of Medinah, during his last illness, and at many other places and times. The Shi'as believe that Muhammad said this hadith so many times because he wanted to stress how important it was that the Muslims only take his own descendants as leaders. The Shi'as believe that this hadith is mutawattir, meaning that it has been related so many times by so many people that there is no doubt about its
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