Al-Muhasibi of Baghdad (Abu Abd Allah al-Harith ibn Asad al-Muhasibi al-Anazi; literally, "he who examines his conscience"), a member of the Shafiite school of Muslim legal thought, is caught up in a persecution of the Mutazilites by leaders of the rival Hanbalite school of jurisprudence, and is compelled to give up his teaching in 846.

In his main work, “Ar-ri ayah li-huquq Allah” (“Book of Observance of What Is Due to God”), al-Muhasibi argues that asceticism should be tempered by attention to the inner and outer duties toward God.

He proposes the use of the rationalist method of rigorous self-examination in anticipation of the Last Judgment (“muha sabah”) to achieve moral purification.

He employs the dialectic vocabulary of the Mutazilites, the founders of Muslim scholasticism, but differs with several of their doctrines.