Can women lead a prayer? Is there something explicitly forbidding women leading men in prayers? Someone has quoted that the Prophet (sws) appointed Ummi Warqa to lead men in prayers? Is that true?

The Sunnah established by the Prophet (sws) in congregational prayers is that only men can lead a prayer.

Dr Muhammad Hamidullah, a famous Muslim scholar has tried to prove through certain indications found in a Hadīth that the Prophet (sws) had appointed Ummi Warqah to lead men in prayers. These indications are quite weak and do not substantiate the claim. Moreover, a Hadīth which contradicts an established Sunnah cannot be accepted.