Sahih Muslim 1821 b
It has been reported on the authority of Jabir b. Samura who said:
I heard the Messenger of Allah (ﷺ) say: The affairs of the people will continue to be conducted (well) as long as they are governed by twelve men. Then the Prophet (ﷺ) said words which were obscure to me. I asked my father: What did the Messenger of Allah (ﷺ) say? He said: All of the (twelve men) will be from the Quraish.
حَدَّثَنَا ابْنُ أَبِي عُمَرَ، حَدَّثَنَا سُفْيَانُ، عَنْ عَبْدِ الْمَلِكِ بْنِ عُمَيْرٍ، عَنْ جَابِرِ بْنِ سَمُرَةَ، قَالَ سَمِعْتُ النَّبِيَّ صلى الله عليه وسلم يَقُولُ ‏"‏ لاَ يَزَالُ أَمْرُ النَّاسِ مَاضِيًا مَا وَلِيَهُمُ اثْنَا عَشَرَ رَجُلاً ‏"‏ ‏.‏ ثُمَّ تَكَلَّمَ النَّبِيُّ صلى الله عليه وسلم بِكَلِمَةٍ خَفِيَتْ عَلَىَّ فَسَأَلْتُ أَبِي مَاذَا قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم فَقَالَ ‏"‏ كُلُّهُمْ مِنْ قُرَيْشٍ ‏"‏ ‏.‏