If a seller informs a buyer of the price of a commodity, he must inform him of all the things that cause the commodity to appreciate or depreciate in value, even if he sells it to him for that price or less than it. For example, he must inform him if he bought it by immediate payment or on credit. In the event that he does not inform him of some of those particulars and afterwards the buyer comes to know them, the buyer can annul the transaction.