The ruling on one who prostrates for forgetfulness, then completes the prayer, and then prostrates for forgetfulness again

Question:
The first question in this episode is one that reached the program from the citizen (A. F. G). He says: Tell us about the ruling on the following prayer: Our imam prayed the midday prayer with us for three units, then prostrated for forgetfulness, then said the closing salam, then stood up and performed the fourth unit, prostrated for forgetfulness, then said the closing salam? May Allah reward you with good.

Answer:
In the name of Allah, the Most Gracious, the Most Merciful. Praise be to Allah, and may Allah send prayers and blessings upon the Messenger of Allah, and upon his family and his Companions, and upon those who follow his guidance. As for what follows:
If the aforementioned imam thought that he had completed the prayer, and said the closing salam after three units, and prostrated for forgetfulness based on the fact that he acted upon certainty, or upon his predominant suspicion, and then he realized that he was mistaken and that he still had one unit remaining, then what is obligatory is what he did: he stands up, performs the fourth unit, and then after reciting the tashahhud and completing it, he says the closing salam, and then prostrates for forgetfulness. This is the most preferable; his prostration is after the salam. If he prostrates before the salam, there is no blame on him. In any case, his action—praise be to Allah—is valid, if it was as we mentioned: he said the closing salam after three units believing that he was correct, then his mistake became apparent to him, so he stood up, completed the prayer, and prostrated for forgetfulness, and praise be to Allah. This is what is obligatory upon him.

The presenter: May Allah reward you with good.