From Sahih Bukhari (Hadith 2620):
Narrated Asma' bint Abu Bakr:My mother came to me during the lifetime of Allah's Messenger (ﷺ) and she was a pagan. I said to Allah's Apostle (seeking his verdict), "My mother has come to me and she desires to receive a reward from me, shall I keep good relations with her?" The Prophet (ﷺ) said, "Yes, keep good relation with her
Reference: Bukhari 2620