From Sahih Bukhari (Hadith 3174):
Narrated ' `Abdullah bin `Abbas:That Abu Sufyan bin Harb Informed him that Heraclius called him and the members of a caravan from Quraish who had gone to Sham as traders, during the truce which Allah's Messenger (ﷺ) had concluded with Abu Sufyan and the Quraish infidels
Reference: Bukhari 3174