I guess he was his wife. Amazing how everyone else is limited to 4 wives. But Allah told Muhammad he could own as many as 9. Allah must have really loved Muhammad. He was also blessed with the strength to 30 men because he apparently had sex with all of his wives every night.
But Muhammad bought, sold, and owned slaves. It seems he even captured them. In the Hadith he actually trades 2 black slaves for 1 Arab slave.