Sunan Ibn Majah — Chapters Regarding Funerals — Hadith No: 1467
Translation
It was narrated that ‘Ali bin Abu Talib said that when he washed the Messenger of Allah (ﷺ) he looked for what which is usually looked for on the deceased (i.e., dirt), and he found none. He said:“May my father be sacrificed for you, you are pure; you were pure in life and you are pure in death.”