Musannaf Ibn Abi Shayba 13:2527

Abu Bakr narrated to us, he said: Ibn Abi Za'idah narrated to us, from Yahya bin Sa'id, from Nafi', from Abu Sa'id, that he heard the Prophet, may Allah bless him and grant him peace, saying: "The dinar for the dinar, and the dirham for the dirham; there is no excess between them. And that which is present shall not be sold for that which is deferred."