(To which kings did the Messenger of Allah, peace be upon him, write letters?)

Anas told that the Prophet wrote to Kisra, Qaisar, the Najashi, and every powerful man, summoning them to God, but it was not the Najashi on whom the Prophet invoked a blessing.* * It says that the Najashi (Negus) of Abyssinia to whom this letter was sent was not the same as the one who ruled at the time when the early emigration from Mecca to Abyssinia took place. Muslim transmitted it.