Sahih Bukhari Volume 9, Book 87, Hadith Number 146.

Narrated By Ibn ‘Umar : Allah’s Apostle said, “(I saw in a dream that) while I was standing at a well and drawing water therefrom, suddenly Abu Bakr and ‘Umar came to me. Abu Bakr took the bucket and drew one or two buckets (full of water), but there was weakness in his pulling, but Allah forgave him. Then Ibn Al-Khattab took the bucket from Abu Bakr’s hand and the bucket turned into a very large one in his hand. I have never seen any strong man among the people doing such a hard job as ‘Umar did, till (the people drank to their satisfaction) and water their camels to their fill and they sat near the water.”