The ruling on speaking after the taslim while forgetting a rak'ah

Question:
If a person misses a rak'ah of the prayer, then forgets and says the taslim, and then the people remind him and he speaks with them, does he stand up and perform the rak'ah he missed, or does the speech that occurred with the praying people who reminded him invalidate his prayer?

Answer:
It does not invalidate his prayer. He stands up and performs what he missed, completes his prayer, and performs the prostration for forgetfulness. His prayer is valid because his speech with those present was for the benefit of the prayer. The Prophet (peace and blessings be upon him) said the taslim after two rak'ahs, then stood up and leaned on a wooden plank in the mosque. They reminded him, saying, "Did you shorten the prayer, O Messenger of Allah, or did you forget?" He said, "I did not shorten it, and I did not forget." Then a man known as Dhu al-Yadayn, named for the length of his arms (may Allah be pleased with him), came to him and said to him: He then performed the prostration for forgetfulness. Yes, and this speech was for the benefit of the prayer, so it does not harm. Yes.