Volume 1, Book 11, Number 662:Narrated Anas:The Prophet said, “Listen and obey (your chief) even if an Ethiopian whose head is like a raisin were made your chief.”
Volume 1, Book 11, Number 664:Narrated Anas bin Malik:The Prophet said to Abu-Dhar, “Listen and obey (your chief) even if he is an Ethiopian with a head like a raisin.”
Volume 9, Book 89, Number 256:Narrated Anas bin Malik:Allah’s Apostle said, “You should listen to and obey, your ruler even if he was an Ethiopian (black) slave whose head looks like a raisin.”
Besides the obvious repetitiveness of the Hadiths (where the instance is mentioned three times, like so many of the other hadiths), these passages show something into Mohammad's mindset.
Mohammad did not like black people.
The fact is Mohammad's principle of slavery was so important to him, that he made sure that a person must remain a slave, EVEN if it meant being owned by a black person. This connotes that blacks were inferior than others, and that the slave trade should be enforced, even if it meant being slave to a person most undesirable, like an Ethiopian black.
To top it off, Mohammad made sure to say that you should remain slaves to blacks whose heads looked like raisins.
The ridiculing of black people just never stopped for Mohammad.