Is it required to exhaustively list every possible attribute when specifying the object of a forward sale?
Chapter on Guaranteed Salaf (Advance Payment) for a Specified Term
Al-Mughni
Book of Sales
Primary text
It is not obligatory to enumerate every single attribute, as this would be impossible and could lead to a situation where the object cannot be delivered at the specified time because items matching all those minute specifications are scarce. Therefore, it is necessary to limit specification to the apparent attributes that significantly affect the price.
Supporting text
If one specifies attributes to such an extreme that the item becomes exceedingly rare at the time of maturity, the forward sale is void because a condition of Salam is that the object must be generally available at the due date, which extreme specification prevents.