(2) باب الأُمَرَاءُ مِنْ قُرَيْشٍ
Narrated Ibn `Umar:
Allah's Messenger (ﷺ) said, "This matter (caliphate) will remain with the Quraish even if only two of them were still existing."
Reference: Sahih al-Bukhari 7140
In-book reference: Book 93, Hadith 4
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 9, Book 89, Hadith 254