It is narrated from Sayyiduna Fadala bin Ubaid (may Allah be pleased with him) that a necklace was brought to the Noble Prophet (peace and blessings be upon him), which contained gold and pearls, and it was for sale, and it had been obtained from the spoils of war. The Prophet (peace and blessings be upon him) ordered that the gold in the necklace be separated, then said: Gold is to be sold for gold in equal amounts.
It is also narrated from Sayyiduna Fadala bin Ubaid, may Allah be pleased with him, who says: On the day of Khaybar, I bought a necklace for twelve dinars, which contained gold and pearls. When I separated them, the gold alone turned out to be worth more than twelve dinars. When I informed the Noble Prophet, peace and blessings be upon him, of this, he said: Do not sell it until it has been separated.
It is also narrated from Sayyiduna Fadala bin Ubaid, may Allah be pleased with him, he says: We were with the Messenger of Allah, peace and blessings be upon him, on the day of the conquest of Khaybar. The Jews sold an uqiyyah of gold in exchange for two or three dinars, but the Messenger of Allah, peace and blessings be upon him, said: Do not sell gold for gold except that it is equal for equal.