Musnad Abu Ya'la al-Mawsili 3:108

Abu Khaythama narrated to us, Jarir narrated to us, from Mansur, from Abd al-Malik, from al-Nazzal ibn Sabra, who said: I prayed Dhuhr with Ali, then he went to a place where he used to sit in the courtyard (al-Rahba), and he sat down, and we sat around him until Asr time arrived. Then a vessel containing water was brought to him. He took a handful from it, rinsed his mouth, inhaled water into his nose, wiped his face and his forearms, wiped his head, and wiped his feet. Then he stood up and drank the remainder of his vessel. Then he said: "I have been told that some men dislike that one of them should drink while standing, but I saw the Messenger of Allah (peace and blessings of Allah be upon him) do that." And this is the ablution of one who has not broken his state of purity.