Sahih al-Bukhari 7142
صحيح البخاري#7142SahihNarrated Anas bin Malik:Allah's Messenger (ﷺ) said, "You should listen to and obey, your ruler even if he was an Ethiopian (black) slave whose head looks like a raisin
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 93:6