The ruling on one who is certain that he left a prostration after the rak'ah has passed

Question:
Our brother says: If I am in doubt about a prostration, and I am in that state of doubt after I have stood up for the bowing in the second rak'ah, and while I am standing, I become certain that I prostrated only once, what should I do? May Allah reward you with good.

Answer:
If you are certain that you left a prostration, you go back and perform the prostration, unless you have already started the recitation; in that case, you continue, and that rak'ah is considered gone, meaning it has passed you by. You make up for it with another rak'ah, and you prostrate for forgetfulness, if you are the imam or praying alone. However, if you are a follower, you perform it after your imam has concluded the prayer. And praise be to Allah.
The point is: if you realize that you left the prostration of this rak'ah when you stand up, or after standing up but before starting the recitation, you go back and perform it, whether you are the imam, praying alone, or a follower. But if you did not know and did not realize it until after the recitation, the rak'ah is invalid, and the second rak'ah takes its place. You perform another rak'ah to make up for it, whether you are the imam, a follower, or praying alone. The imam prostrates for forgetfulness, and the one praying alone prostrates for forgetfulness. Yes.

The presenter : May Allah reward you with good, and may He do you good.