​Sahih Bukhari (Gifts – 56)
Narrated Asma’ bint Abu Bakr (ra), My mother came to me during the lifetime of Allah’s Messenger (pbuh) and she was a Mushrikah (polytheist, idolatress, pagan). I said to Allah’s Messenger (pbuh) (seeking his verdict), “My mother has come to and she desires to recieve a reward from me, shall I keep good relations with her ?” The Prophet (pbuh) said, “Yes, keep good relation with her.”