Aḥmad ibn Ḥanbal (d. 241/855), renowned for his profound knowledge of hadith--the reports of the Prophet's sayings and deeds--is a major figure in the history of Islam. Ibn Ḥanbal's piety and austerity made him a folk hero, especially after his principled resistance to the attempts of two Abbasid caliphs to force him to accept rationalist doctrine. His subsequent imprisonment and flogging became one of the most dramatic episodes...