Joseph Schacht quotes a hadith by Muhammad that is used "to justify reference" in Islamic law to the 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 "Tabi‘un" ("successors" of the companions) "was the rule", while use of hadith of Muhammad himself by Muslims was "the exception". Schacht credits Al-Shafi‘i — founder of the Shafi'i school of "fiqh" (or "madh'hab") — with establishing the principle of the use of the hadith of Muhammad for Islamic law, and emphasizing the inferiority of hadith of anyone else, saying hadiths