Musnad Ahmad 658:150

'Affan narrated to us, Sulayman ibn al-Mughirah narrated to us, Humayd ibn Hilal narrated to us, Yunus narrated to us, from al-Bara' who said: We were with the Messenger of Allah (peace and blessings of Allah be upon him) on a journey, and we came upon a well with little water. Six of us descended into it, and I was the seventh, or seven of us, and I was the eighth. He said: It was a shallow well. A bucket was lowered to us, and the Messenger of Allah (peace and blessings of Allah be upon him) was at the edge of the well. I filled it halfway or about a third of it, and I raised the bucket to the Messenger of Allah (peace and blessings of Allah be upon him). Al-Bara' said: I almost used my vessel to see if I could find anything to put in my throat, but I found nothing. He dipped his hand into it and said what Allah willed for him to say, and the bucket was returned to us with what was in it. The last of us was pulled out with a garment for fear of drowning. Then it [the water] surged. 'Affan said once: out of fear of drowning.