Is prayer valid behind an Imam whose religious innovation or immorality is unknown?
Chapter on Imamate and Congregational Prayer
Al-Mughni
Book of Prayer
Primary text
If the Imam's immorality or innovation is not known until after praying behind them, one must repeat the prayer, based on a ruling from Ahmad. The prayer is valid if the Imam conceals their innovation or immorality, as this is analogous to unknowingly praying behind someone who is defiled or has broken ablution. However, if the Imam publicly displays their transgression, repetition is required, as the transgression prevents valid followership, similar to being *Umi* (illiterate regarding Quran) or having impurity, where knowledge of the condition does not negate the obligation of repetition.
Supporting text
Ibn 'Aqil argued that repetition is not required if the condition is hidden, likening it to impurity or the state of ablution. However, the correct view is that repetition is only obligatory behind one who openly declares their deviation, a state unlikely to be concealed.