كتاب الإمارة
33  
The Book on Government
(8)
Chapter: The obligation of obeying leaders in matters that do not involve sin, but it is forbidden to obey them in sinful matters
(8)
باب وُجُوبِ طَاعَةِ الأُمَرَاءِ فِي غَيْرِ مَعْصِيَةٍ وَتَحْرِيمِهَا فِي الْمَعْصِيَةِ ‏‏
Sahih Muslim 1838 b

This hadith has been transmitted on the authority of Shu'ba with the same chain of transmitters, and he said:

"An Abyssinian slave."
وَحَدَّثَنَاهُ ابْنُ بَشَّارٍ، حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، وَعَبْدُ الرَّحْمَنِ بْنُ مَهْدِيٍّ، عَنْ شُعْبَةَ، بِهَذَا الإِسْنَادِ وَقَالَ عَبْدًا حَبَشِيًّا ‏.‏
Reference : Sahih Muslim 1838b
In-book reference : Book 33, Hadith 57
USC-MSA web (English) reference : Book 20, Hadith 4529
  (deprecated numbering scheme)