The Book Pertaining to the Excellent Qualities of the Holy Prophet (may Peace be upon them) and His Companions (Kitab Al-Fada'il)
Muslim :: Book 30 : Hadith 5723
Anas reported Allah's Messenger (may peace be upon him) as saying: I served the Messenger of Allah (may peace be upon him) for nine years, and I do not know (of any instance) when he said to me: Why you have done this and that, and he never found fault with me in anything.