It has been narrated on the authority of Anas that the Prophet of Allah (ﷺ) wrote to Chosroes (King of Persia), Caesar (Emperor of Rome), Negus (King of Abyssinia) and every (other) despot inviting them to Allah, the Exalted. And this Negus was not the one for whom the Messenger of Allah (ﷺ) had said the funeral prayers.
Reference | : Sahih Muslim 1774a |
In-book reference | : Book 32, Hadith 91 |
USC-MSA web (English) reference | : Book 19, Hadith 4382 |
(deprecated numbering scheme) |