Is it permissible to take a commission from the buyer when selling tires that are not included in the sales target and go into the company's account without benefit to the seller, given that he is an intermediary between the company and the buyer?

An employee is not permitted to take commission from a buyer for personal gain unless authorized by their employer. If authorization is not given, the employee may not take anything from the buyer without the company's knowledge, even if it is offered without being requested. Rather, it must be handed over to the company, based on the saying of the Prophet, peace and blessings be upon him: "O people, whoever among you works for us on a task and conceals from us a needle or more, it is an ill-gotten gain, and he will come with it on the Day of Resurrection."