Musnad Ahmad 304:2

Waki’ narrated to us, he said: Hisham ibn ‘Urwah and Ibrahim ibn Isma’il narrated to us, from Abu Wajzah al-Sa’di, from a man from Muzaynah, from ‘Umar ibn Abi Salamah, that food was brought to the Prophet, may Allah bless him and grant him peace. He said: "O ‘Umar"—Hisham said: "O my son"—"mention the name of Allah, the Mighty and Majestic, eat with your right hand, and eat from what is nearest to you." He said: So that has remained my way of eating ever since.