When is a sale legally binding after the parties separate?
Chapter on the Option of the Two Parties in Sale
Al-Mughni
Book of Sales
Primary text
The sale becomes legally binding after the parties separate unless there exists a reason permitting invalidation. This is demonstrated by the Prophet's saying: If they separate after transacting and neither party retains the right to cancel the sale, the sale is confirmed, and another narration states: The two sellers (parties) have an option until they separate, making separation the limit of the option period. Following separation, the sale is obligatory, unless a defect is discovered in the item, allowing for its return, or if the seller stipulated a specific duration for the option, granting the right to return within that period. There is no dispute among scholars regarding the validity of return based on these two circumstances, supported by the Prophet's saying: The believers adhere to their conditions.
Supporting text
Analogous to a defect is if the item is misrepresented (tadlis) in a manner that affects the price, or if a characteristic is stipulated that differs from the reality, establishing the option. Similarly applicable is the case where the seller misrepresents the payment terms in a cost-plus sale (Murabaha), such as claiming a price is immediate when it is deferred.