Musnad Ahmad 33:407

'Abd al-Samad ibn 'Abd al-Warith narrated to us, 'Abd al-'Aziz ibn Muslim narrated to us, al-Husayn narrated to us, from Salim ibn Abi al-Ja'd, from Jabir, who said: The people became thirsty on the day of al-Hudaybiyyah, and the Messenger of Allah (peace and blessings of Allah be upon him) had a small leather water container in front of him from which he was performing ablution. The people rushed toward him, so he said: "What is the matter with you?" They said: "O Messenger of Allah, we have no water to drink, nor do we have water to perform ablution with, except for what is in front of you." The Messenger of Allah (peace and blessings of Allah be upon him) placed his hand into the container, and the water began to gush from between his fingers like the springs. So we drank and performed ablution. I (the narrator) said: "How many were you?" He said: "If we had been one hundred thousand, it would have sufficed us; we were fifteen hundred."