What is the ruling on praying behind an infidel (*Kafir*)?
Chapter on Imamate and Congregational Prayer
Al-Mughni
Book of Prayer
Primary text
The prayer behind an infidel is invalid in all circumstances, whether his infidelity is discovered after completing the prayer or before. All those who prayed behind him must repeat the prayer. This is the position of Ash-Shafi'i and the companions of opinion (*Ahl ar-Ra'y*).
Supporting text
Abu Thur and Al-Muzani hold that there is no need to repeat the prayer if one was unaware of the Imam's infidelity, equating it to praying behind someone in a state of major impurity whose impurity was unknown, similar to praying behind one who is ritually impure without knowledge. Our evidence is that one prayed behind someone not qualified for prayer, invalidating the prayer, similar to praying behind a madman, whereas in ritual impurity, knowledge of one's own impurity is a condition [for the invalidity of the follower's prayer], whereas the infidel knows his own status.