Musnad Ahmad 32:2041

'Affan narrated to us, Abu 'Awanah narrated to us, from Isma'il al-Suddi, who said: I asked Anas ibn Malik, I said: "Did the Messenger of Allah, peace and blessings of Allah be upon him, perform the funeral prayer over his son Ibrahim?" He said: "I do not know. May the mercy of Allah be upon Ibrahim; had he lived, he would have been a truthful prophet." He said: I said: "How do I turn when I have finished the prayer? To my right or to my left?" He said: "As for me, I saw the Messenger of Allah, peace and blessings of Allah be upon him, turn to his right."