I said to Abu Abdillah (as): "We deal with some people from the rural areas and others. We sell to them and make a profit - sometimes ten becomes twelve, and sometimes ten becomes thirteen. We allow them to defer payment for a year or so, and they provide us with a written guarantee secured by their house or land for the amount, including the added profit. We then agree that if they bring the payment within the specified time, we will cancel the sale and return the property to them. However, if the deadline passes and they do not bring the payment, the property becomes ours. What do you think about this transaction?" Imam (as) said: "I see that it is yours if they fail to meet the condition. But if they bring the payment within the agreed time, you must return the property to them."