Musnad Abu Ya'la al-Mawsili 130:13

Abu al-Rabi' narrated to us, Hammad narrated to us, 'Abd al-'Aziz ibn Suhayb narrated to us, from Anas, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Eat the pre-dawn meal (suhur), for indeed there is blessing in the pre-dawn meal."