Musnad Ahmad 27:523

Muhammad ibn Bishr narrated to us, Ubaydullah narrated to us, Abu Bakr ibn Salim narrated to me, from Salim ibn Abdullah, from Abdullah ibn Umar, that the Prophet (peace and blessings of Allah be upon him) said: "I was shown in a dream that I was drawing water with a bucket and a pulley from a well. Then Abu Bakr came and drew one or two buckets, and he drew with a weak pull—may Allah forgive him. Then Umar ibn al-Khattab came and drew water, and it transformed into a large bucket. I have not seen a genius among the people who performs his work as he did, until the people drank their fill and watered their camels."