An example of this is where one says, “I lease you my house for one year for one hundred riyals, beginning today.” The other says, “Yes, but I have the option for one month.” According to the author’s view—which is the standard position of the school—this is not valid, because the lease term immediately follows the contract. According to the stronger view, however, it is valid. Thus, the contract is concluded and the tenant takes up residence; then, after twenty days have passed, he rescinds the lease. We say: There is nothing wrong with this, but you must pay the customary market rent for the period during which you occupied it.
Nothing has now been lost by either the tenant or the lessor. We say that the tenant owes the customary market rent, rather than the proportional amount of the agreed rent, because once the contract is rescinded, it is annulled retroactively, and it becomes clear that there was no contract. When a person derives benefit from another’s property without a valid contract, he must pay its customary market rent.
This is the correct view in this issue, because, in reality, it neither permits what is unlawful nor prohibits what is lawful, nor does it cause either party to lose a right. Both parties have agreed to this condition, since the owner of the house will in fact receive his due, and the tenant will likewise receive his due. There is therefore no excessive uncertainty in it.
There may be a need for this arrangement. A person may need to lease this house for one year for such-and-such an amount, saying, “I have the option for one month, because my own house is presently under construction and may perhaps be completed before the month ends.” The correct view, then, is that a stipulated option is valid, even if its period immediately follows the contract, or if the lease term begins before the stipulated option period has ended. If the party holding the option rescinds the contract, the period during which the tenant occupied the house is assessed according to the customary market rent.
The author remained silent concerning matters that were discussed under the option of the contracting parties meeting and did not mention them here, such as currency exchange. He stated that a stipulated option is valid in a sale, but did not state that a stipulated option is valid in currency exchange, because currency exchange requires