Musannaf Ibn Abi Shayba 36:168

It was narrated to us by Abd al-Rahim ibn Sulayman, from Isra'il, from Simak, from Ikrimah, from Ibn Abbas, who said: It was said to the Messenger of Allah, may Allah bless him and grant him peace, when he finished from Badr: "You should go for the caravan, for there is nothing else besides it." Al-Abbas called out to him while he was a captive in his bonds, "That is not correct." The Messenger of Allah, may Allah bless him and grant him peace, said: "Why?" He said: "Allah promised you one of the two groups, and He has given you what He promised you."