Musnad Ahmad 1153:1088

Yazid narrated to us, he said: Hisham informed us, from Budayl, from Abdullah ibn Ubayd ibn Umayr, from Aisha, that the Prophet, peace and blessings of Allah be upon him, was eating food with six of his companions. A Bedouin came and ate it in two morsels. The Prophet, peace and blessings of Allah be upon him, said: "As for him, had he mentioned the name of Allah, it would have sufficed you all. So when one of you eats food, let him mention the name of Allah. If he forgets to mention the name of Allah at its beginning, let him say: 'In the name of Allah, at its beginning and its end.'"