The ruling on the prostration for forgetfulness when the ma'mum joins the prayer in the third rak'ah

Question : For example, the one who did not catch up with him. Let us assume that the Prophet (peace and blessings be upon him) was in the second rak'ah, or that he caught up with him in the second.

Answer : Yes, for example, if the imam is traveling and he is in the second rak'ah, but the ma'mum joined him in the third, then he does not prostrate. That is the complete ruling.