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
Hadith terminology terminology, it refers to a "hadith" not fulfilling all of the conditions necessary to be deemed "mutawatir". "Hadith ahad" consists of three sub-classifications also relating to the number of narrators in the chain or chains of narration: An "ʻaziz" () "hadith" is any "hadith" conveyed by two narrators at every point in its "isnād" (chain of narrators). A "gharib" () "hadith" is one conveyed by only one narrator. Al-Tirmidhi's understanding of a "gharib hadith", concurs to a certain extent with that of the other traditionists. According to him a "hadith" may be classified as "gharib" for one of the following