What is the ruling on selling online in the following cases: displaying goods that the seller does not possess and adding a profit before purchasing them for the customer, or buying and possessing the goods before selling them to the customer with added profit, or the customer describing a good that the seller does not own, and the seller buys it for him at a price lower than that agreed upon with the customer to make a profit?

The transaction mentioned in the second question is valid if the questioner concludes a sale contract for a commodity he owned before selling it. As for the two scenarios mentioned in the first and third questions, they involve the issue of selling what one does not possess, unless it is a salam (forward) sale, where the commodity is described as being in one's liability, something that can be precisely described, and the full price is paid at the contract session, and it is delivered to the buyer at a known future date. The third scenario can be conducted as an agency contract for a fee, where the questioner acts as an agent for the customer in purchasing the commodity for one thousand Riyals, in exchange for a known and agreed-upon fee of five hundred Riyals, and he must be truthful about the price.