Musannaf Ibn Abi Shayba 3:3225

Ahmad ibn Abd al-Malik ibn Waqid narrated to us, from Ubayd Allah ibn Umar, from Abdullah ibn Muhammad ibn Aqil, from Ata ibn Yasar, from Abu Sa’id al-Khudri, who said: The Prophet, peace and blessings of Allah be upon him, used to eat on the day of al-Fitr before he would go out.