Is a seller of printing devices considered to have wronged the buyer after amending the quantity of cups sold, if their number or color was not explicitly mentioned in the advertisement, and the buyer was not prevented from inspecting or inquiring?

For a sale to be valid, the sold item must be known, either by sight or by description. This is because uncertainty regarding the sold item constitutes gharar (undue risk or deception), which is prohibited in Islamic law. Therefore, if the sale was conducted online and all the cups were photographed in a way that their number was clear, then the sale is valid. In this case, the seller must provide the buyer with any missing items or seek their forgiveness. However, if the picture did not show the number of cups, the sale is invalid. In this scenario, the sale must be re-conducted by specifying the number of cups and devices sent, and a new price must be determined by mutual agreement between the two parties. If the sale was concluded after the buyer saw the devices and cups and knew their number, then the sale is valid. However, if the buyer did not see the sold items because they were inside a carton, and the number of cups was unknown, then the sale is invalid, and the method of correction is as mentioned.