Sahih al-Bukhari, Hadith 7142 ⓘ
Narrated Anas bin Malik: Allah's Messenger said, "You should listen to and obey, your ruler even if he was an Ethiopian (black) slave whose head looks like a raisin."
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا يَحْيَى، عَنْ شُعْبَةَ، عَنْ أَبِي التَّيَّاحِ، عَنْ أَنَسِ بْنِ مَالِكٍ ـ رضى الله عنه ـ قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " اسْمَعُوا وَأَطِيعُوا وَإِنِ اسْتُعْمِلَ عَلَيْكُمْ عَبْدٌ حَبَشِيٌّ كَأَنَّ رَأْسَهُ زَبِيبَةٌ " .
also referenced under: Book 93, Hadith 6 (In-Book) & Volume 9, Book 89, Hadith 256 (USC-MSA)