Musnad Abu Ya'la al-Mawsili 152:5

Muhammad ibn Bashar Bundar narrated to us, Abd al-Rahman ibn Mahdi narrated to us, Abu Bakr ibn Ayyash narrated to us, from Asim, from Zirr, from Abdullah ibn Mas'ud, from the Prophet, may Allah bless him and grant him peace, who said: "Eat the pre-dawn meal (suhur), for indeed there is blessing in the pre-dawn meal."