Yahya related to me from Malik from Zayd ibn Aslam from Ata ibn Yasar that Muawiya ibn Abi Sufyan sold a gold or silver drinking-vessel for more than its weight. AbudDarda said, "I heard the Messenger of Allah, may Allah bless him and grant him peace, forbidding such sales except like for like." Muawiya said to him, "I dont see any harm in it." Abud-Darda said to him, "Who will excuse me from Muawiya? I tell him something from the Messenger of Allah, may Allah bless him and grant him peace, and he gives me his own opinion! I will not live in the same land as you!" Then Abud-Darda went to Umar ibn al-Khattab and mentioned that to him. Umar ibn al-Khattab therefore wrote to Muawiya, "Do not sell it except like for like, weight for weight."Malik said, "If, when counterpoising gold for gold or silver for silver, there is a difference of weight, one party should not give the other the value of the difference in silver or something else. Such a transaction is ugly and a means to usury because if one of the parties were permitted to take the difference for a separate price, it could be as if he had bought it separately, so he would be permitted. Then it would be possible for him to ask for many times the value of the difference in order to permit the completion of the transaction between the two parties.