What is the difference between selling what I do not own by proxy and selling what I do own? Does a mere intention, written contract, or verbal agreement make a difference in rendering the sale permissible or impermissible? Or does the market only accept advance payment?

Agency differs from purchasing from a distributor in several ways: In agency, the commodity remains the property of the distributor and under their guarantee. The agent does not pay the distributor money for it, and the agent's profit is often restricted by what the principal determines. It is not required for the agent to own or possess the commodity to sell it. As for purchasing, the commodity becomes the property of the buyer and under their guarantee. The buyer pays its value, and they can sell it for any profit they wish. They must own and possess the commodity before selling it to another, based on the Prophet's (peace be upon him) saying: "If you buy a commodity, do not sell it until you take possession of it," and his saying: "The profit of what has not been guaranteed is not permissible."