What is the ruling on the prayer of an Imam who experiences bleeding or impurity during prayer?

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If the Imam experiences nosebleed (ru'af), bleeding, or emission of seminal fluid (madhy), he should withdraw and instruct the congregation to complete their prayer. Al-Zuhri stated this ruling. Al-Shafi'i, in his later opinion, preferred that the congregation pray individually in such a circumstance. It is suggested that Ahmad's reservation regarding succession might have been specifically about the act of appointing a successor, not the validity of the followers' prayer, especially since Ahmad ruled that the followers' prayer is not invalidated by the Imam laughing.