Sahih Bukhari
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
Volume: 005 / Book Number: 059 / Hadith Number: 310
Narrated 'Abdur-Rahman bin 'Auf:
"I had an agreement with Umaiya bin Khalaf (that he would look after my relatives and property in Mecca, and I would look after his relatives and property in Medina)." 'Abdur-Rahman then mentioned the killing of Umaiya and his son on the day of Badr, and Bilal said, "Woe to me if Umaiya remains safe (i.e. alive) . "