The ruling on adding a rak'ah in prayer for the one who joins late

Question:
A man entered the prayer with the congregation and prayed one rak'ah with the imam. Then the imam prostrated for forgetfulness, and then he said the closing salam. This man realized, while making up the remainder of his prayer, that the imam had added one rak'ah to the prayer. Is it permissible for this man to count that extra rak'ah (which the imam added to the prayer), or must he start the prayer anew without counting that extra rak'ah which he prayed with the imam?

Answer:
If the imam adds a rak'ah to the prayer due to forgetfulness, the one who joined late must not count it, because it occurred due to the imam's forgetfulness, which is the stronger of the two opinions among the scholars. He must pray the prayer in full, and prostrate for forgetfulness after he has finished making up what is due from him, if he did not prostrate with the imam for forgetfulness. If he did prostrate with him for forgetfulness, that suffices him. And success is from Allah.