Hazrat Imam Muhammad Baqir (a.s.) says:
“One day the Holy Prophet (S) was passing through the bazār of Madinah. He (S) told a wheat seller, ‘Your wheat is of a good quality.’ Then he put his hands inside the pile and found inferior quality of wheat below He said, ‘I see that you have gathered the provisions of Khayanat and adulteration.’”2
Allamah Hilli says that a man asked Imam Ja’far as-Sadiq (a.s.), “If a person has two types of goods one is of a superior and expensive quality and the other is of inferior and cheap quality, can he mix these two and sell at a special rate?”
Imam (a.s.) replied,
“It is not correct for him to sell the adulterated goods to Muslims. However (there is no harm) if he informs them (of the adulteration).”3
Dawūd Ibn Sujān asked Imam Ja’far as-Sadiq (a.s.): “I had two varieties of musk. One was wet, the other dry. I sold the wet and fresh musk but no one was prepared to buy the dry one at the same rate. Is it permitted for me to make it wet so that it is sold out?” Imam (a.s.) told him,
“It is not allowed. However if you inform the buyer that you have made it wet, it is another matter.”