Sahih Al Bukhari – Book of Wills And Testaments (Wasaayaa)

Volumn 004, Book 051, Hadith Number 029.
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Narated By Anas RA: When Allah's Apostle PBUH came to Medina; he did not have any servant. Abu Talha (Anas' step-father) took me to Allah's Apostle and said, "O Allah's Apostle! Anas is a wise boy, so let him serve you." So, I served him at home and on journeys. If I did anything, he never asked me why I did it, and if I refrained from doing anything, he never asked me why I refrained from doing it.