Abu Salih says that I heard Abu Sa'id (may Allah be pleased with him) saying that gold should be sold for gold with equal weight. I met Ibn Abbas (may Allah be pleased with them both), so I asked him, "The thing you say, do you find its proof in the Qur'an, or have you heard anything about it from the Prophet (peace and blessings be upon him)?" He replied, "I have not found this in the Book of Allah, nor have I heard it directly from the Prophet (peace and blessings be upon him), but Usamah bin Zaid (may Allah be pleased with him) has informed me that the Prophet (peace and blessings be upon him) said: 'Riba (usury) is related to credit.'"