What is the ruling of Islamic law regarding a muezzin who has memorized the Quran and leads people in prayer, but denied an act and swore by Allah concerning it, and that was a false oath (yameen ghamoos), and he has not repented? Must he be removed from leading the prayer?

The ruling on praying behind an immoral person (fasiq) and a liar has been clarified, as well as what should be done concerning a lying Imam. A person’s oath not to do something, which they then do, does not necessarily constitute an intentional lie or a false oath (yamin (definition) ghamus), as they might have forgotten what they did. Furthermore, the validity of repentance does not require it to be witnessed.