What is the ruling on an employee of a financing company taking a commission for directing clients to purchase a commodity from a specific supplier without the company's knowledge, and what is the ruling on the supplier paying this commission?

If the company does not prohibit the referral and it does not affect the work, then there is no harm in the employee taking a commission from the shop owner. What is considered is that it does not cause harm to the employer. If no harm occurs, then there is nothing against the employee, as mentioned by Ibn Qudamah.