Musnad Ahmad 1122:1

Yazid ibn Harun narrated to us, Muhammad ibn Ishaq informed us, from Yazid ibn Abi Habib, from Marthad ibn Abdullah al-Yazani, from Hudhayfah al-Azdi, from Junadah al-Azdi, who said: I entered upon the Messenger of Allah, peace and blessings of Allah be upon him, on a Friday, among seven men of the Azd, and I was the eighth of them, while he was eating lunch. He said, "Come to the lunch." We said, "O Messenger of Allah, we are fasting." He said, "Did you fast yesterday?" We said, "No." He said, "Will you fast tomorrow?" We said, "No." He said, "Then break your fast." So we ate with the Messenger of Allah, peace and blessings of Allah be upon him. He said: When he went out and sat on the pulpit, he called for a vessel of water, and he drank while he was on the pulpit, and the people were looking, showing them that he does not fast on Friday.