Ruling on the latecomer’s sufficiency with the prostration of forgetfulness along with the imam

Question:
He says: One day I entered the mosque during the Maghrib prayer and found that I was behind by one rak'ah. The imam made a mistake after the first tashahhud, and after the second tashahhud, the imam prostrated for forgetfulness, and I prostrated with him. After the taslim, I stood up and prayed the rak'ah in which the imam had gone ahead of me, recited the tashahhud, and said the taslim. After I left the mosque, one of the worshippers told me that my prayer was invalid because, after I prayed the rak'ah in which I was behind, I did not prostrate for forgetfulness. Is my prayer truly invalid? I ask for your guidance. May Allah reward you with good.

Answer:
Your prayer is valid, and this fatwa has no basis. You prostrated with your imam, following him, and praise be to Allah. As for you, you do not owe the prostration. However, if the imam had not prostrated until after the taslim, and you had not prostrated with him, then it is prescribed for you to prostrate after making up what you owed, because you did not prostrate with the imam. But you did prostrate with the imam, and the matter is concluded, praise be to Allah. Yes.

The presenter : May Allah reward you with good.