The ruling on alerting the praying congregation to the imam's error

Question:
May Allah reward you. If you have finished your prayer and another group comes to pray, and the imam makes a mistake, either in the prayer or in the recitation, is it obligatory for me to alert them, or should I leave them alone until they finish the prayer?

Answer:
This concerns the people praying behind him. If he makes a mistake in the recitation, they recite it for him. If he forgets, they make tasbih for him. This concerns those behind him. As for you, as for the recitation, the matter is easy; you alert him to the error. As for alerting him to forgetfulness in the prayer, you are patient until he finishes, because he may make up for it. Perhaps the congregation will alert him and he will make up for it by prostrating for forgetfulness. If none of this happens, then you alert them, both them and him, to what occurred. The Messenger of Allah (peace and blessings be upon him), when a man entered the mosque and prayed, then came and greeted the Prophet (peace and blessings be upon him), he returned the greeting and said to him: "Go back and pray, for you have not prayed." He did not alert him during the prayer, but rather alerted him after he had finished the prayer. Yes.