Question
If it becomes apparent that the imam was in a state of ritual impurity during the prayer, the follower must repeat their prayer; because the imam is a guarantor. Why must they repeat it, when the principle is that the imam is a guarantor?
Answer
I say, and with God's help: The imam guarantees that if the imam's prayer is valid, he can carry the prayer of others. If his prayer is not valid, he cannot guarantee or carry the prayer of others. And God knows best.