What is the ruling on a man who works for his father buying tires with his own money to sell them in installments to his friend who requested a loan? Is it permissible for him to sell them to his father? Is it permissible for him to trade in this commodity without his father's permission? Is it permissible for him to direct his friend to merchants to sell the tires? What is the ruling on selling what you do not possess? Is it permissible for the one who bought the tires in installments to sell them for cash?

The basic ruling is that buying and selling in installments is permissible if it adheres to the Sharia guidelines. If the buyer's intention in purchasing is not to utilize the commodity but rather to sell it to obtain cash (tawarruq), then it is permissible if it adheres to the Sharia guidelines. However, if the buyer sells the commodity to your father with prior collusion, it is not permissible because it is a stratagem to facilitate usury (riba). Furthermore, you are not permitted to commit to buying the tires from the buyer after he has sold them to you. You are allowed to trade in tires without your father's permission, provided that it is not during official working hours at his shop. It is not permissible for anyone to sell what they do not own, except in the case of a salam (forward) sale, which is authorized by Sharia.