Musnad Ahmad 32:1446

Yunus narrated to us, Abu 'Awanah narrated to us, from 'Abd al-'Aziz ibn Suhayb and Qatadah, from Anas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Eat the pre-dawn meal (suhur), for indeed there is blessing in the pre-dawn meal."