From Sahih Bukhari (Hadith 2624):
Narrated Asma' bint Abu Bakr (ra):My mother came to me during the lifetime of Allah's Messenger (ﷺ) and she was a Mushrikah (polytheist, idolatress, pagan). I said to Allah's Messenger (ﷺ) (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 (ﷺ) said, "Yes, keep good relation with her
Reference: Bukhari 2624