Language:
كتاب الأدب
78  
Good Manners and Form (Al-Adab)
(8)
Chapter: Kindness by a lady who has a husband, to her mother
(8)
باب صِلَةِ الْمَرْأَةِ أُمَّهَا وَلَهَا زَوْجٌ
Sahih al-Bukhari 5979
Narrated Asma':
"My mother who was a Mushrikah (pagan, etc.), came with her father during the period of peace pact between the Muslims and the Quraish infidels. I went to seek the advice of the Prophet (ﷺ) saying, "My mother has arrived and she is hoping (for my favor)." The Prophet (ﷺ) said, "Yes, be good to your mother."
وَقَالَ اللَّيْثُ حَدَّثَنِي هِشَامٌ، عَنْ عُرْوَةَ، عَنْ أَسْمَاءَ، قَالَتْ قَدِمَتْ أُمِّي وَهْىَ مُشْرِكَةٌ فِي عَهْدِ قُرَيْشٍ وَمُدَّتِهِمْ، إِذْ عَاهَدُوا النَّبِيَّ صلى الله عليه وسلم مَعَ أَبِيهَا، فَاسْتَفْتَيْتُ النَّبِيَّ صلى الله عليه وسلم فَقُلْتُ إِنَّ أُمِّي قَدِمَتْ وَهْىَ رَاغِبَةٌ ‏{‏أَفَأَصِلُهَا‏}‏ قَالَ ‏ "‏ نَعَمْ صِلِي أُمَّكِ ‏"‏‏.‏
Reference : Sahih al-Bukhari 5979
In-book reference : Book 78, Hadith 10
USC-MSA web (English) reference : Vol. 1, Book 73, Hadith 9
  (deprecated numbering scheme)