Is a sale considered void if 50 ardabs of wheat were purchased, the price was paid in full, and the type was specified, but the seller made delivery contingent upon his acquisition of the wheat from another seller, and delivery was delayed for four months due to a legal dispute between the seller and his seller, and is the buyer entitled to demand payment or a refund of the price regardless of this dispute?

If the contract is for wheat owed by the seller, it is a salam (forward) contract, and the delivery date must be specified, based on the Prophet's (peace be upon him) saying: "Whoever pays in advance for something, let it be for a known measure, a known weight, to a known term." A salam contract in which the term is not known is an invalid salam, and the price must be returned to its owner.

However, if the contract is for wheat that the seller purchased from another person, then it is the sale of a debt to someone other than the debtor, and the sale of a bartered foodstuff before taking possession of it, which is impermissible.