Hadith as Sunna, but it is not necessary that a Sunna would have a supporting hadith sanctioning it. Some sources (Khaled Abou El Fadl) limit hadith to verbal reports, with the deeds of Muhammad and reports about his companions being part of the "Sunnah", but not hadith. Joseph Schacht quotes a Hadith by Muhammad that is used "to justify reference" in Islamic law to companions of Muhammad as religious authorities — "My companions are like lodestars." According to Schacht, (and other scholars) in the very first generations after the death of Muhammad, use of hadith from "Sahabah" ("companions" of Muhammad) and
Introduction to the Science of Hadith adding six terms in the process). The first pertains to the "matn" (text) of the hadith and its three divisions and 30 types. The three divisions are "ṣaḥīḥ", "ḥasan", and "ḍa`īf". The thirty types include those mentioned in hadith terminology and others. The second deals with the "isnād" (chain of narration) and comprises 11 types. These types generally fall within the discipline of biographical evaluation. The third category includes six types: the qualifications necessary for conveying hadith, the manners in which they are transmitted, the transcription of hadith, and the etiquette of the narrator and of the student. The fourth