Musnad Ahmad 5:441

Waki’ narrated to us, Shu’bah narrated to me, from ‘Abd al-Malik ibn Maysarah, from an-Nazzal ibn Sabrah, that when ‘Ali prayed the Dhuhr prayer, he called for a vessel of water in the open courtyard. He drank while he was standing, then he said: "Indeed, some men dislike this, but I saw the Messenger of Allah (peace and blessings of Allah be upon him) do as you have seen me do." Then he wiped himself with the remainder of it and said: "This is the ablution of one who has not broken his state of purity."