Musnad Ahmad 31:291

Al-Muttalib narrated to us, Ibn Abi Layla narrated to us, from Atiyyah al-Awfi, from Abu Sa’id al-Khudri, that the Messenger of Allah, may Allah bless him and grant him peace, said: "Take the Suhur (pre-dawn meal), for indeed there is blessing in the Suhur."