17. Safwan has narrated from Ishaq ibn ‘Ammar who has said the following: “This is concerning my question before abu ‘ Abd Allah عليه السلام, about the case of a man who came to me with dirham to sell them to me for the dirhams with me. He certainly did not want dinars but he wanted the dirham and he did not leave until he took my dirham. I bought from him dirham in exchange for dinars. His dinars were not with me in complete form so I borrowed from my neighbor and gave to him and perhaps I did not pay attention how much it weighed. He (the Imam) said, Is it, not the case that he takes it to offset what belongs to him?’ I replied, ‘Yes, that is true. He (the Imam) said, ‘It is not unlawful/”