Is it permissible for a wholesaler to grant a discount to retailers, provided that the discount is not given until the end of a specified period and after fulfilling certain conditions related to the value of purchases, knowing that this discount is agreed upon in advance, and the sale is often on deferred payment?

As long as the sale is deferred, and the discount from the price is agreed upon in the contract, this poses a problem for the certainty of the price, which is a condition for the validity of the sale. However, some scholars believe that such an ambiguity is forgivable if its outcome leads to certainty, and that the prohibiting ambiguity is that which leads to dispute. So, if the ambiguity does not lead to dispute, it does not prevent the validity of the sale.