Sayyiduna Ibn Abbas (may Allah be pleased with them both) said that the Messenger of Allah (peace and blessings be upon him) said: "Take the black people to yourselves, for three of them are among the chiefs of the people of Paradise: Luqman the Wise, the Negus (al-Najashi), and Bilal the mu'adhdhin." Imam al-Tabarani (may Allah have mercy on him) said: By this he meant the Abyssinians.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11434