Musannaf Ibn Abi Shayba 1:607

Ali ibn Mushir narrated to us, from Yahya ibn Ayyub al-Bajali, from Abu Zur'ah, who said: I entered upon Abu Hurayrah, and he performed ablution (wudu) up to his shoulders and up to his knees. I said to him, "Will you not suffice with what Allah has obligated upon you regarding this?" He said, "Yes, but I heard the Messenger of Allah (peace and blessings of Allah be upon him) saying: 'The extent of the adornment (hilyah) reaches the extent of the ablution.' So I liked for my adornment to be increased."