Musannaf Ibn Abi Shayba 27:332

Ali ibn Mushir narrated to us, from Muhammad ibn Amr, from Abu Salamah, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "While I was drawing water at a well, Ibn Abi Quhafah (Abu Bakr) came and drew a bucket or two, and there was weakness in his drawing, and may Allah forgive him. Then Umar came and drew until it transformed in his hand into a large bucket, and he watered the people at the resting place (the watering trough). I have never seen a genius (abqari) perform such a feat as he did."