It is narrated from Sayyiduna Ja'far bin Abi Talib (may Allah be pleased with him) that the Negus (al-Najashi) asked him: What is your religion? He said: A Messenger was sent among us whose speech, truthfulness and faithfulness we know. He invited us to worship Allah alone, associating nothing with Him, and to abandon what our people and others used to worship besides Him. He commanded us to do good and forbade us from evil, and he commanded us to pray, to fast, to give charity and to maintain the ties of kinship. So he invited us to what we recognised, and he recited to us a revelation that came from Allah, the like of which there is no other speech. So we affirmed him, believed in him, and knew that what he brought is the truth from Allah. At that, our people separated from us; they harmed us and oppressed us. When they had brought us to a point we disliked, and we had no strength to protect ourselves from them, we came out to your land and preferred you over others. The Negus said: Go, you are safe in my land; whoever insults you will have to pay a fine.
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 1466