وما لا يمكن ضبط صفته ولا يعرف مقداره لا يجوز السلم فيه
Translation: Salam is not valid where attributes cannot be specified and quantity cannot be determined.
The converse is that salam fails where substantial variation cannot be controlled through adequate description and quantity. “One rare gemstone of some suitable quality later” may leave both the item's identity and its defining characteristics uncertain.
This is more than memorizing an inventory of prohibited names. The practical question is whether, on the delivery date, both parties can identify the same objectively specified goods without having to negotiate basic terms again.
Opening interactive controls...
When description or quantity cannot be controlled
Bab al-Salam: Fabric, Gems, Bricks and Precise Specification
وما لا يمكن ضبط صفته ولا يعرف مقداره لا يجوز السلم فيه
Translation: Salam is not valid where attributes cannot be specified and quantity cannot be determined.
The converse is that salam fails where substantial variation cannot be controlled through adequate description and quantity. “One rare gemstone of some suitable quality later” may leave both the item's identity and its defining characteristics uncertain.
This is more than memorizing an inventory of prohibited names. The practical question is whether, on the delivery date, both parties can identify the same objectively specified goods without having to negotiate basic terms again.