Permissibility of joining the imam with the intention of a voluntary prayer for one who has already prayed the obligatory prayer

A person prayed the four-rak'ah obligatory prayer and went to another mosque intending to pray for the funeral, but he found the imam in the third rak'ah of the obligatory prayer, i.e., near the end of the prayer. Does he join them with the intention that it is a voluntary prayer?The Shaykh: Yes,This is asking, he says: He arrived at another mosque after having prayed the obligatory prayer and found that they had already prayed two rak'ahs. He joined them in the remaining two rak'ahs with the intention that it was a voluntary prayer. Is this permissible?We say: Yes, it is permissible.

The questioner: What if he had joined from the beginning of the prayer?The Shaykh: If he joins from the beginning of the prayer, it is permissible, and he should follow them.