Musnad Ahmad 1017:49

Abu Ubaydah al-Haddad narrated to us, Thawab ibn Utbah narrated to us, from Abdullah ibn Buraydah, from his father, who said: The Prophet, peace and blessings of Allah be upon him, on the day of al-Fitr, would not go out until he had eaten, and on the day of al-Nahr, he would not eat until he had returned.