The imam prayed the 'Asr prayer with three rak'ahs; should he repeat the prayer or add another rak'ah?

Question:
The listener asking is Shaykh Hasan Shaykh from Syria. He sent a question and says: If the imam forgets in the 'Asr prayer and prays three rak'ahs, and none of the ma'mum (those praying behind him) remind him, and then he says the taslim (closing salam), does he pray the last rak'ah or does he prostrate the prostration for forgetfulness? May Allah reward you with good.

Answer:
In the name of Allah, the Most Gracious, the Most Merciful. Praise be to Allah, Lord of the worlds, and may Allah send prayers and blessings upon our Prophet Muhammad, his family, and his Companions. As for what follows: If he says the taslim before completing the prayer due to forgetfulness, and he realizes that he has left something of the prayer, even after the taslim, he stands up and performs what he left of the prayer, whether he left one rak'ah or more, and completes the prayer, and prostrates for forgetfulness, provided the interval is not long. If the interval is long, or he leaves the mosque, or a long time has passed, he repeats the prayer from the beginning. However, if the interval is short, he stands up and performs what was missing from the prayer, sits for the final tashahhud, and recites the final tashahhud, then says the taslim, then prostrates two prostrations after the taslim. This is the preferred method. And if he prostrates before the taslim, there is no harm. Yes.