Abdul Malik bin Ubaid says: I was present with Abu Ubaidah bin Abdullah bin Mas'ud when two men came to him. They had made a transaction for some goods, but the buyer claimed that he had bought the goods for a certain amount, and the seller claimed that he had sold it for a different amount. Abu Ubaidah said: A similar issue was brought to our master Abdullah bin Mas'ud (may Allah be pleased with him). He said: I was present with the Messenger of Allah (peace and blessings be upon him) when a similar issue was presented to him. The Messenger of Allah (peace and blessings be upon him) ordered the seller to swear an oath on his claim, then gave the buyer the choice: if he wished, he could take the goods at that price, and if he wished, he could cancel the transaction altogether.