Abu Aziz bin Umayr, the brother of Sayyiduna Mus'ab bin Umayr (may Allah be pleased with him), narrates: On the day of Badr I was among the captives. The Prophet (peace and blessings be upon him) said: "Accept the counsel to treat the captives well." The narrator says: I was among some of the Ansar, and whenever they had their morning or evening meal, they would eat the dates themselves and feed me wheat; that was because of the instruction of the Prophet (peace and blessings be upon him).
Al-Tabarani recorded it in al-Mu'jam al-Saghir and al-Mu'jam al-Kabir, and its chain is hasan (good).