Is it permissible to pray behind an Imam who writes amulets, does not pray Fajr or Isha in congregation, and dislikes those who shorten their garments and grow their beards, knowing that he is in good health despite his old age? And if it is not permissible, is it then permissible to pray individually while he is leading the prayer in congregation?

It is impermissible for a fasiq (open sinner) to lead the prayer. However, if he is a regular imam, the validity of praying behind him depends on the nature of his sin. If he writes polytheistic amulets (tamâ'im shirkîya), then it is not permissible to pray behind him, and it must be clarified that his act is shirk (polytheism). But if the amulets are permissible, then praying behind him is valid, although his action is disliked.

As for other sins, such as not attending Fajr and Isha prayers, shaving the beard, letting one's garment hang below the ankles (isbal), and his dislike for those who grow their beards and shorten their garments—these do not invalidate the prayer behind him, according to the preponderant opinion, though they are disliked.

The imams have agreed on the dislike of praying behind a fasiq, but they differed on its validity, and the correct view is that it is valid.

If the fasiq is a mosque imam and does not repent, he must be removed if possible and if no discord arises. Otherwise, one should pray behind someone else from among the righteous if available, as a deterrent to him. If it is not possible to pray behind someone else, then praying behind him is legislated to achieve the benefit of the congregation. If there is fear of discord from praying behind someone else, then one should pray behind him to avert the discord.