Musnad Abu Ya'la al-Mawsili 150:416

Muhammad ibn Bakkar narrated to us, Abu Ma’shar narrated to us, from Sa’id, from ‘Aishah, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: “O ‘Aishah, if I had wished, mountains of gold would have traveled with me. An angel came to me—if I were to describe him, he would be equal to the Ka’bah—and said: ‘Indeed, your Lord sends you peace and says to you: If you wish, [be] a prophet-servant, and if you wish, [be] a prophet-king.’” He said: “So I looked at Jibril, and he gestured to me to humble myself.” He said: “So I said: ‘A prophet-servant.’” He said: “The Messenger of Allah (may Allah bless him and grant him peace) would not eat while reclining after that. He would say: ‘I eat as the servant eats, and I sit as the servant sits.’”