Sahih Bukhari Volume 4, Book 53, Hadith Number 399.

Narated By ‘ 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 Apostle had concluded with Abu Sufyan and the Quraish infidels.