The Book of Virtue, Good Manners and Joining of the Ties of Relationship (Kitab Al-Birr was-Salat-I-wa'l-Adab)
Muslim :: Book 32 : Hadith 6181
Abu Huraira reported that a person said: Allah's Messenger, who amongst the people is most deserving of my good treatment? He said: Your mother, again your mother, again your mother, then your father, then your nearest relatives according to the order (of nearness).