Sahih Muslim 1774
Sahih Muslim · Book 32: The Book of Jihad and Expeditions · The Prophet (saws) wrote to the Kings of the Kuffar, inviting them to Islam
وَحَدَّثَنِيهِ نَصْرُ بْنُ عَلِيٍّ الْجَهْضَمِيُّ ، أَخْبَرَنِي أَبِي ، حَدَّثَنِي خَالِدُ بْنُ قَيْسٍ ، عَنْ قَتَادَةَ ، عَنْ أَنَسٍ ، وَلَمْ يَذْكُرْ وَلَيْسَ بِالنَّجَاشِيِّ الَّذِي صَلَّى عَلَيْهِ النَّبِيُّ صلى الله عليه وسلم .
It has been narrated on the authority of the same narrator through another chain of transmitters with the same difference in the wording.