Harb bin Shaddad narrates from Yahya bin Abi Kathir a similar hadith with the same meaning. And the Negus was a Muslim; there is evidence of this in the words of the Prophet (peace and blessings be upon him) that we have narrated.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنائز / 7030