أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ الأَعْلَى، قَالَ حَدَّثَنَا خَالِدٌ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ يَحْيَى بْنِ حُصَيْنٍ، قَالَ سَمِعْتُ جَدَّتِي، تَقُولُ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ فِي حَجَّةِ الْوَدَاعِ " وَلَوِ اسْتُعْمِلَ عَلَيْكُمْ عَبْدٌ حَبَشِيٌّ يَقُودُكُمْ بِكِتَابِ اللَّهِ فَاسْمَعُوا لَهُ وَأَطِيعُوا " .
It was narrated that Yahya bin Husain said: "I heard my grandmother say: 'I heard the Messenger of Allah say, during the Farewell Pilgrimage: If an Ethiopian slave is appointed over you who rules according to the Book of Allah, then listen to him and obey."' Translation Not Available
Book Ref: Sunan An Nisai Book 39 Hadith 4192
Web Ref: Sunan An Nisai Vol 5 Book 39 Hadith 4197