Musnad Abu Ya'la al-Mawsili 115:289

Ubayd Allah narrated to us, [saying] Yazid ibn Zuray' and Khalid ibn al-Harith narrated to us, all of them from Sa'id, from Qatadah, from Anas, that the Messenger of Allah (may Allah bless him and grant him peace) said: "Eat the suhur (pre-dawn meal), for indeed there is blessing in the suhur."