This work explores the earliest extant discussions on the authority of the Hadith in Islam and compares them with contemporary debates. These lively and often polemical debates are mostly popular discussions in which Muslims from different backgrounds and cultures participate - making this topic relevant to Muslims in their daily lives, as well as a question of academic interest. What makes this book unique is that it is the first study to take into account both the earliest and most recent discussions of the oral tradition of the prophet Muhammad. The book also includes the first Western language translation of al-Shafi'i's Kitab Jima' al-'Ilm, which articulates arguments that were critical in establishing the position of the Hadith in mainstream Islam.