Musnad Ahmad 775:18

Muhammad ibn Ja'far and Hajjaj narrated to us, they said: Shu'bah narrated to us, he said: I heard Abu al-Mukhtar from the tribe of Banu Asad, he said: I heard Abdullah ibn Abi Awfa say: The Messenger of Allah, peace and blessings of Allah be upon him, and his companions were struck by thirst. He said: So he descended at a place, and a vessel was brought to him. He began to give his companions to drink, and they began to say: "Drink." The Messenger of Allah, peace and blessings of Allah be upon him, said: "The one who gives the people to drink is the last of them." Until he had given them all to drink.