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 "with something, such as numerous chains of narration, strengthening it." Ibn Hajar's definitions indicate that there are five conditions to be met for a particular "hadith" to be considered "ṣaḥīḥ": A number of books were authored in which the author stipulated the inclusion of "ṣaḥīḥ hadith" alone. According to Ahl al-Sunna, this was only achieved by the first two books in the following list: "Ḥasan" ( meaning "good") is used to describe "hadith" whose authenticity is not as well-established as that of "ṣaḥīḥ hadith", but sufficient for use as supporting evidence. Ibn Hajar defines a "hadith" that is "ḥasan lithatihi"""ḥasan"