Praying Behind a Sinner (FATWA)
What do the scholars of the religion say in the following matter:
Is it permissible, at any time, to pray ṣalāh behind a fornicator/adulterer and an alcoholic?
When the resident imām is present, he appoints anyone else as imām, is this permissible or not?
There is no permission to perform ṣalāh behind a fornicator/adulterer or an alcoholic at any time. But, where the Jumu’ah and prayers of the two `Eīds are held only in one location and the imām is a fāsiq, they could be performed behind him and the Jumu`ah should be repeated by performing the four rak`āt of Ẓuhr. In other than Jumu`ah and the two `Eīds, if the imām appoints someone else who is suitable to be imām as the imām, there is no problem in this. Rather, if the other is greater than him in knowledge and scholarship, then the other is even better than him.
Allāh E knows best
Imām Aḥmad Raḍā Khān V