Hanash bin Abdullah (may Allah have mercy on him) narrates: We were with Sayyiduna Fadalah bin Ubayd (may Allah be pleased with him) in the campaign of Rhodes, and a necklace containing gems, pearls and gold fell to the share of myself and my companions. My companions said to me: "Buy it from us, and we will give you a concession (on the price)." I said: "No, not until I ask Sayyiduna Fadalah bin Ubayd (may Allah be pleased with him)." So I asked him, and he said: "Remove the gold and put it in one pan of the scale, and put the other gold in the other pan, and do not take anything except like for like, for I heard the Messenger of Allah (peace and blessings be upon him) say: 'Whoever believes in Allah and the Last Day, let him not take anything except like for like.'"
Hadith Referenceالمعجم الكبير للطبراني / باب الفاء / 15867