Sahih al-Bukhari 2978
صحيح البخاري#2978SahihNarrated Ibn `Abbas:Abu Sufyan said, "Heraclius sent for me when I was in 'Ilya' (i.e. Jerusalem). Then he asked for the letter of Allah's Messenger (ﷺ) and when he had finished its reading there was a great hue and cry around him and the voices grew louder and we were asked to quit the place. When we were turned out, I said to my companions, 'The cause of Ibn Abi Kabsha has become conspicuous as the King of Bani Al- Asfar is afraid of him
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: 56:187