Musnad Ahmad 33:415

Muhammad ibn Sabiq narrated to us, Ibrahim ibn Tahman narrated to us, from Abu al-Zubayr, from Jabir, who said: A man among us fasted while we were with the Messenger of Allah, peace and blessings of Allah be upon him, on one of his military expeditions. He mentioned its meaning. He said: Then the Messenger of Allah, peace and blessings of Allah be upon him, called for a cup. He raised it upon his hands, then he drank so that the people would see that he was not fasting.