Musnad Ahmad 1007:122

Hashim narrated to us, Shaiban narrated to us, from Yahya, from Abdullah ibn Abi Qatadah, from his father, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "When one of you drinks, let him not breathe into the vessel. And when one of you urinates, let him not touch his private part with his right hand. And when one of you cleans himself after relieving himself, let him not clean himself with his right hand."