Musnad Ahmad 27:366

Rawh narrated to us, Ibn Jurayj narrated to us, he said: Musa ibn Uqbah informed me, Salim narrated to me, from Ibn Umar, regarding the dream of the Messenger of Allah, peace and blessings of Allah be upon him, concerning Abu Bakr and Umar. He said: "I saw the people gathered, then Abu Bakr stood up and drew a bucket or two, and there was weakness in his drawing, and may Allah forgive him. Then Umar drew, and it transformed into a large bucket, and I have not seen a genius among the people who could perform his feat, until the people watered their camels and they rested at the watering place."