Hadith 698
Sayyiduna Anas bin Malik (may Allah be pleased with him) reports: The Prophet (peace and blessings be upon him) had two servants, one was Abyssinian and the other was Coptic. One day, they insulted each other; one said, "O Abyssinian!" and the other said, "O Copt!" The Prophet (peace and blessings be upon him) said: "Do not say this, both of you are men of the family of Muhammad (peace and blessings be upon him)."