Musnad Ahmad 27:1404

'Affan narrated to us, Hammad ibn Salamah narrated to us, 'Asim ibn al-Mundhir informed me, he said: We were in an orchard of ours, or of 'Ubaydullah ibn 'Abdullah ibn 'Umar, shooting arrows. The prayer time arrived, so 'Ubaydullah stood up to a water basin in the orchard, in which there was a camel hide, and he began to perform ablution from it. I said: "Do you perform ablution from it while this hide is in it?" He said: "My father narrated to me that the Messenger of Allah (peace and blessings of Allah be upon him) said: 'When water is two qullahs or three, it does not become impure.'"