Hadith report, the scale of the report's transmission, the routes through which the report was transmitted, and the individual narrators involved in its transmission. On the basis of these criteria, various classifications were devised for hadith. The earliest comprehensive work in hadith studies was Abu Muhammad al-Ramahurmuzi's "al-Muhaddith al-Fasil", while another significant work was al-Hakim al-Naysaburi's "Ma‘rifat ‘ulum al-hadith". Ibn al-Salah's "ʻUlum al-hadith" is considered the standard classical reference on hadith studies. By means of hadith terminology, hadith are categorized as "ṣaḥīḥ" (sound, authentic), "ḍaʿīf" (weak), or "mawḍūʿ" (fabricated). Other classifications used also include: "ḥasan" (good), which refers to an otherwise
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