Ruling on the follower following the imam in the prostration for forgetfulness after he has stood up

Q: The brother (M. S. A.) from Riyadh says in his question: I stood up to make up what I missed after the imam’s taslim, and after a few moments the imam prostrated for forgetfulness—meaning after the taslim—so I prostrated with him. Then I stood up and prayed what I had missed. Is what I did valid? If not, what must I do? Please give us a ruling, and may Allah reward you.

A: You did well in what you did, and you owe nothing; because the Prophet (peace and blessings be upon him) said: . And if you had completed your prayer and then prostrated for forgetfulness after completing it, there is nothing wrong with you; because you had intended to separate in order to make up what was required of you. May Allah grant success to everyone.