Sahih al-Bukhari 7541
صحيح البخاري#7541SahihAnd Ibn 'Abbas narrated:Abu Sufyan bin Harb told me that Heraclius called for his translator and then asked for the letter of the Prophet (ﷺ), and the former read it (thus): "In the Name of Allah, the Most Gracious, the Merciful. (This letter is) from Muhammad bin 'Abdullah, to Heraclius. "...O people of the Scripture (Jews and Christians): Come to a word that is just between us and you that we worship none but Allah..." (V.3:)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 97:166