Musannaf Ibn Abi Shayba 17:1337

Ya'la narrated to us, he said: Abu Hayyan narrated to us, from 'Abayah, who said: I performed wudu for Ibn 'Umar, and I stood to his right, pouring water upon him. When he finished, he raised his gaze and said: "From where did you take this etiquette?" I said: "From my grandfather, Rafi'." He said: "There is the man."