Musnad Ahmad 31:825

Al-Hakam ibn Nafi’ narrated to us, Sa’id ibn ‘Abd al-‘Aziz narrated to us, from ‘Atiyyah ibn Qays, from Qaza’ah, from Abu Sa’id al-Khudri, who said: "The Messenger of Allah (peace and blessings of Allah be upon him) commanded us to depart in the year of the Conquest, when two nights of Ramadan had passed. We went out fasting, until we reached al-Kadid, whereupon the Messenger of Allah (peace and blessings of Allah be upon him) commanded us to break the fast. So the people became two groups: among them was the one who fasted, and the one who broke the fast."