Musnad Abu Ya'la al-Mawsili 42:374

Zuhayr narrated to us, Zakariyya ibn ‘Adi narrated to us, ‘Ubayd Allah ibn ‘Amr narrated to us, from ‘Abd Allah ibn Muhammad ibn ‘Aqil, from ‘Ata’ ibn Yasar, from Abu Sa’id al-Khudri, who said: The Messenger of Allah (may Allah bless him and grant him peace) used to eat on the day of Fitr before he went out, and he would not pray before the prayer. Then, when he returned, he would pray two rak'ahs.