And the explanation of the evidence that the conversation of such a person performing prayer does not invalidate the prayer.

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) led us in two units of prayer from the two evening prayers, either Zuhr or Asr—I think it was the Zuhr prayer. Then the Prophet (peace and blessings be upon him) came to the wooden post in the direction of the qiblah in the mosque and leaned his hands on it, placing one hand over the other. The hasty people left the mosque, saying that the prayer had been shortened. Among the people were Sayyiduna Abu Bakr and Umar (may Allah be pleased with them both), but they were afraid to speak to the Prophet (peace and blessings be upon him). A man, who was called Dhu’l-Yadayn (the one with two hands) because his hands were either short or long, said,“O Messenger of Allah, has the prayer been shortened or have you forgotten?”The Prophet (peace and blessings be upon him) said,“Neither has the prayer been shortened nor have I forgotten.”So he said,“Rather, you have forgotten.”The Prophet (peace and blessings be upon him) asked,“Is Dhu’l-Yadayn telling the truth?”They replied,“Yes.”The Prophet (peace and blessings be upon him) then performed the remaining two units, then gave salam, then said takbir and performed a prostration like his usual prostration or even longer, then raised his head from prostration, (then performed a second prostration). Bundar narrated the complete hadith. Imam Abu Bakr (may Allah have mercy on him) said: I have mentioned this complete chapter in“The Book of Forgetfulness in Prayer.”