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
Criticism of Hadith "in the early Islamic centuries there could be no better way of promoting a cause, an opinion, or a faction than to cite an appropriate action or utterance of the Prophet." This gave strong incentive to fabricate hadith. According to Daniel Brown, the major causes of corruption of Hadith literature are: Other criticism made of ahadith include Orthodox Muslims do not deny the existence of false "hadith", but believe that through the work of hadith scholars, these false "hadith" have been largely eliminated. al-Shafi'i himself, the founder of the proposition that “sunna” should be made up exclusively of specific precedents