From Sahih Bukhari (Hadith 3491):
Narrated Kulaib bin Wail: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
Reference: Bukhari 3491