Hazrat Dinar says that I asked Hasan (may Allah have mercy on him): How is it to sell a commodity saying, "I am free from boils, wounds, blisters on hands and feet, and every apparent and hidden defect"? He (may Allah have mercy on him) replied: You will not be free (of liability) until you specify, "I am free from the defect of this eye and the defect of this thing." If you do not say so, the commodity will be returned to you.