It is, however, tied to a definite period that may not be exceeded; the length of the option varies with the commodity itself.

Thus, for textiles—whether fine cloth, ordinary garments, other merchandise, or stored grain, edible or otherwise, and the like among movable goods—the option for either party runs for anything up to three days.
For slaves it extends to the span of a week.
For riding animals it lasts the amount of time normally needed to test-ride a courier’s mount or something comparable.
For houses and the rest of real estate the option may last up to one month.
For perishable foodstuffs sold in the marketplace, as well as fish and fresh fruit, the period is about an hour, the shortest of all being for live, freshly-caught fish.
In no case may the option exceed the term assigned to that category; each class of goods is given a span deemed appropriate to it, provided no fear of spoilage exists.

It is not permissible to stipulate spot payment in a sale that includes an option. Should the buyer nevertheless pay the price in cash of his own accord, I hope that this will be acceptable.
Likewise, one may not require immediate payment for absent goods—whether animals or anything else—unless they are located only a day or two away, or something similar.
An exception is made for houses and land: spot payment may be stipulated for them even when they are out of sight.

It is allowed to make the option for the seller, for the buyer, or for both together.
Each of them may also attach the option to a third person, saying for instance, “If so-and-so is satisfied,” or “pending so-and-so’s counsel,” unless that person is far away; if he is at a distant remove, the sale does not take effect on that basis and is invalid.
And whoever stipulates the option