Is fulfilling customer requests for products not currently in stock considered selling what one does not own? Is it permissible to add a reasonable commission when marketing products for another company? What is Bay' al-Salam (forward buying), and how can it be applied in online marketing?

If a customer requests a product that is unavailable, it is not permissible to conclude a sales contract for it before acquiring possession of it. Instead, this would be a promise to sell, or an agreement on a commission in exchange for procuring it, with the customer's knowledge of the commission. Another solution is the salam sale, where an agreement is made with the customer to deliver a described product at a known future date, and the full price is paid at the time of the contract. The manager's permission to sell goods at a specific price, with any excess belonging to you, is permissible.