Musnad Abu Ya'la al-Mawsili 117:31

Ibrahim ibn al-Hajjaj al-Sami narrated to us, Abu Thabit 'Abd al-Wahid ibn Thabit narrated to us, Thabit narrated from Anas, who said: The Prophet, may Allah bless him and grant him peace, used to like to break his fast with three dates or something that fire had not touched.