Musnad Ahmad 5:656

Yazid narrated to us, Mis'ar informed us, from 'Abd al-Malik ibn Maysarah, from al-Nazzal ibn Sabrah, who said: A vessel of water was brought to 'Ali, and he drank while he was standing. Then he said: "It has reached me that some people dislike that one of them should drink while standing, but I have seen the Messenger of Allah, peace and blessings of Allah be upon him, do just as I have done." Then he took from it and wiped [his face and hands], and said: "This is the ablution of one who has not broken his state of purity."