Musnad Ahmad 30:2319

Hassan ibn Musa narrated to us, Shaiban ibn Abd al-Rahman narrated to us, Yahya ibn Abi Kathir narrated to us, from Abu Salamah ibn Abd al-Rahman, from Abu Hurairah, who said: While I was praying the Dhuhr prayer with the Messenger of Allah, may Allah bless him and grant him peace, the Messenger of Allah, may Allah bless him and grant him peace, performed the taslim after two rak'ahs. A man from Banu Sulaym stood up and said: "O Messenger of Allah, has the prayer been shortened, or have you forgotten?" The Messenger of Allah, may Allah bless him and grant him peace, said: "The prayer has not been shortened, nor have I forgotten." He said: "O Messenger of Allah, you only prayed two rak'ahs." The Messenger of Allah, may Allah bless him and grant him peace, said: "Is what Dhu al-Yadayn says true?" They said: "Yes." He said: So he stood up and prayed two more rak'ahs with them. Yahya said: Damdam ibn Jaws narrated to me that he heard Abu Hurairah saying: Then the Messenger of Allah, may Allah bless him and grant him peace, performed two prostrations.