Sayyiduna Anas bin Malik (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) had two slaves, one an Abyssinian and the other a Copt. One day the two argued, and one of them said: "O Abyssinian!" and the other said: "O Copt!" The Prophet (peace and blessings be upon him) said: "Do not both speak like this! You are both men belonging to the family of Muhammad."
Al-Tabarani recorded it in al-Mu'jam al-Saghir. Its chain contains a narrator, Yazid bin Abi Ziyad, and he is layyin (weak). The rest of its narrators are thiqat (trustworthy).
Abu Ya'la also recorded it similarly, in the same way.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأدب / 13060