Ruling on following the imam when he stands for an extra rak'ah

Question:
A man prayed the obligatory prayer in congregation, and this man missed one rak'ah of the obligatory prayer. The imam made a mistake and prayed an extra rak'ah beyond the prescribed number. Does the latecomer say the taslim with the congregation, or does he complete the rak'ah he missed?

Answer:
This man does not stand up for the extra rak'ah if he knows it is an addition; he sits with the people. Likewise, the congregation does not stand up; they alert him by saying, "Subhan Allah, Subhan Allah," and they do not stand up with him. If he returns to the correct state, praise be to Allah. If he does not return, they are patient until he says the taslim, because he may believe he is correct. When he says the taslim, they say the taslim with him, if they believe he is mistaken; they do not stand up with him.
Likewise, the one who missed a rak'ah does not stand up with him if he knows it is an addition. When the imam says the taslim, he stands up and makes up the rak'ah he missed, because making up a missed prayer is only after the taslim, after the imam's taslim. If he stood up with him while ignorant, not knowing that it was an addition, it does not suffice him according to the correct opinion. Rather, he makes it up after that; when the imam says the taslim, he makes it up. This is the correct view.

The presenter : May Allah reward you with good.