What is the ruling on the commission I took in exchange for purchasing and supplying filters for a company I work for, with the addition of a profit margin and splitting the commission with the owner of a supply company?

The purchase for the company or individual can be done in two ways: First, that he buys the commodity for himself and then sells it to them. He is a seller who profits from them, and he is not obligated to inform them of the amount of his profit. However, the price of the commodity must be within the customary price, and he must take possession of the commodity before selling it. Second, that he acts as an agent on their behalf for the purchase. In this case, he must disclose to them the real price at which he bought it, and he cannot profit from them except with their knowledge. He may agree with them on a fee for this agency. It is a breach of trust to appear as an agent while being a seller who profits without their knowledge. Honesty is obligatory in dealings, and lying and taking people's money unjustly are not permissible. So, if someone's brother commissions him to buy something, it is not permissible for him to take an amount greater than the real price, just as it is not permissible for the seller to write an unreal price on the invoice. And whoever is not prepared for the work or it is not customary for him to do it for a fee, if he performs it, he is considered a volunteer unless he stipulates a fee before the work.