Hadith same text are each counted as individual ahadith. If, say, ten companions record a text reporting a single incident in the life of Muhammad, hadith scholars can count this as ten hadiths. So Musnad Ahmad, for example, has over 30,000 hadiths—but this count includes texts that are repeated in order to record slight variations within the text or within the chains of narrations. Identifying the narrators of the various texts, comparing their narrations of the same texts to identify both the soundest reporting of a text and the reporters who are most sound in their reporting occupied experts of hadith
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