It is narrated from Hazrat Imran bin Husain that the Noble Prophet (peace and blessings be upon him) prayed three rak‘ahs and then turned away. Then a man, who was called Khirbaq, stood up towards him. He said, "O Messenger of Allah (peace and blessings be upon him)! Has the prayer become shortened?" The Prophet (peace and blessings be upon him) asked, "What happened?" He replied, "You have prayed three rak‘ahs." So the Prophet (peace and blessings be upon him) prayed one more rak‘ah, then gave salam, and performed sajdah sahw, then gave salam again. And (Imam) Abu Hanifa's opinion is mentioned that: when the one praying engages in conversation, then he will not perform sajdah sahw (rather, he will repeat the prayer).