Sahih Bukhari Volume 5, Book 57, Hadith Number 31.

Narated By ‘Abdullah bin ‘Umar : The Prophet said, “In a dream I saw myself drawing water from a well with a bucket. Abu Bakr came and drew a bucket or two weakly. May Allah forgive him. Then ‘Umar bin Al-Khattab came and the bucket turned into a very large one in his hands. I had never seen such a mighty person as he in doing such hard work till all the people drank to their satisfaction and watered their camels that knelt down there.