Hadith 1820
Chapter 1: The people follow the Quraish and the Caliphate belongs to the Quraish - كتاب الإمارة
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 " .
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),
Reference : Sahih Muslim 1820
In-book reference : Book 33, Hadith 4
USC-MSA web (English) reference : Book 20, Hadith 4476