Musnad Ahmad 5:796

Abdullah narrated to us, Abu Khaythama narrated to me, and Ishaq ibn Isma'il narrated to us, they both said: Jarir narrated to us, from Mansur, from Abd al-Malik ibn Maysara, from al-Nazzal ibn Sabra, who said: We prayed Dhuhr with Ali, may Allah be pleased with him. He then went to a place where he used to sit in the courtyard (al-Rahba), and he sat down, and we sat around him. Then the time for Asr arrived. A vessel was brought to him, and he took a handful from it, rinsed his mouth, sniffed 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. I saw the Messenger of Allah, may Allah bless him and grant him peace, do as I have done."