Sahih Muslim
The Book of Jihad and Expeditions — Hadith #4478
Scholarly Consensus: Sahih How we grade
حَدَّثَنِي يُوسُفُ بْنُ حَمَّادٍ الْمَعْنِيُّ، حَدَّثَنَا عَبْدُ الأَعْلَى، عَنْ سَعِيدٍ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، أَنَّ نَبِيَّ اللَّهِ صلى الله عليه وسلم كَتَبَ إِلَى كِسْرَى وَإِلَى قَيْصَرَ وَإِلَى النَّجَاشِيِّ وَإِلَى كُلِّ جَبَّارٍ يَدْعُوهُمْ إِلَى اللَّهِ تَعَالَى وَلَيْسَ بِالنَّجَاشِيِّ الَّذِي صَلَّى عَلَيْهِ النَّبِيُّ صلى الله عليه وسلم .
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.
Hadith Grading
Each grade below reflects one scholar's assessment of the chain of transmission. The grade describes the chain, not the Prophet's words. How we grade
Scholarly Consensus: Sahih