Sahih Muslim
Sahih Muslim 1820
The people follow the Quraish and the Caliphate belongs to the Quraish
Arabic hadith text
وَحَدَّثَنَا أَحْمَدُ بْنُ عَبْدِ اللَّهِ بْنِ يُونُسَ، حَدَّثَنَا عَاصِمُ بْنُ مُحَمَّدِ بْنِ زَيْدٍ، عَنْ أَبِيهِ، قَالَ قَالَ عَبْدُ اللَّهِ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم "لاَ يَزَالُ هَذَا الأَمْرُ فِي قُرَيْشٍ مَا بَقِيَ مِنَ النَّاسِ اثْنَانِ "
Translation
It has been narrated on the authority of 'Abdullah that the Messenger of Allah (ﷺ) said
The Caliphate will remain among the Quraish even if only two persons are left (on the earth),