Musnad Ahmad 31:824

Abu al-Mughirah narrated to us, Sa'id ibn 'Abd al-'Aziz narrated to us, he said: 'Atiyyah ibn Qays narrated to me, from the one who narrated to him, from Abu Sa'id al-Khudri, who said: "The Messenger of Allah (peace and blessings of Allah be upon him) gave us notice of departure in the year of the Conquest, when two nights of Ramadan had passed. We went out fasting until we reached al-Kadid, then the Messenger of Allah (peace and blessings of Allah be upon him) commanded us to break the fast. So the people became such that among them were those who were fasting, and among them were those who had broken the fast. Until we reached the nearest encampment facing the enemy, he commanded us to break the fast, and we all broke our fast."