I asked Zainab bint Abi Salama (i.e. daughter of the wife of the Prophet, "Tell me about the Prophet ﷺ . Did he belong to the tribe of Mudar?" She replied, "Yes, he belonged to the tribe of Mudar and was from the offspring of An-Nadr bin Kinana."
حَدَّثَتْنِي رَبِيبَةُ النَّبِيِّ ﷺ زَيْنَبُ ابْنَةُ أَبِي سَلَمَةَ قَالَ قُلْتُ لَهَا أَرَأَيْتِ النَّبِيَّ ﷺ أَكَانَ مِنْ مُضَرَ قَالَتْ فَمِمَّنْ كَانَ إِلاَّ مِنْ مُضَرَ مِنْ بَنِي النَّضْرِ بْنِ كِنَانَةَ