What is the ruling if the imam remembers after the prayer that he was not in a state of wudu?

Question : A man prayed in congregation for one of the obligatory prayers, and when they finished the prayer and dispersed, he remembered that he was not in a state of wudu. What is required of him? And does the congregation have to repeat the prayer?

Answer : This imam who led the congregation in prayer without wudu, forgetting, and then remembered after finishing the prayer, has no sin upon him because he was forgetful. This falls under the saying of Allah the Exalted: So Allah said, "I have done so." But his prayer is not valid because of the saying of the Prophet (peace and blessings be upon him): So he has to repeat the prayer. As for the followers who prayed behind him while not knowing that he was in a state of ritual impurity, their prayers are valid because they prayed in the manner they were commanded to, so they are not required to repeat it.