“This is concerning my question before abu ‘Abd Allah (a.s.), about the case of a man who has various kinds of the same item of foodstuff of the same price of which one is of high quality and one is of low quality but he mixes them together; then sells them for one kind of price. He (the Imam) said, ‘It is not proper for him and it is cheating the Muslims unless he informs them of the condition.’”