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 its source. This provides confirmation that the "hadith" is authentically attributed to its source at a level above reasonable doubt. This is due to its being beyond historical possibility that narrators could have conspired to forge a narration. In contrast, an "ahaad hadith" is a narration the chain of which has not reached a number sufficient to qualify as "mutawatir". "Hadiths" can be "mutawatir" in both actual text and meaning: The second category, "ahaad" ( meaning "singular") narration, refers to any "hadith" not classified as "mutawatir". Linguistically, "hadith ahad" refers to a "hadith" narrated by only one narrator. In "hadith"