Musannaf Ibn Abi Shayba 13:2299

Abu Bakr narrated to us, he said: Ibn Abi Za’idah narrated to us, from Yazid ibn Ibrahim, from al-Hasan, regarding a man who buys gold with dirhams, so he weighs the dinar and it is in excess, and he takes [something] for its excess. He said: "There is no harm in it." Ibn Sirin disliked that and said: "Take with it a collection of gold, and with half of it silver."