Ruling on the agent accepting a gift from the seller when purchasing for his principal

Question:
In the last of this questioner's questions, she says: My husband works at one of the schools, and the school principal asked him to buy some equipment for the school. He reached the lowest price with one of the companies he purchased from, and then the company owner gave him a small amount of money, deducting it from the value of the equipment, and said: It is a gift for him from the company. The husband took this amount. Is it forbidden or lawful?

Answer:
Leaving it is safer; because it may be from the category of ... so that he does not buy from anyone but him. Leaving it is safer; because he may leave the other stores and not buy from anyone but this one; because he gives him some of the money.
So what should be done is to leave this; because the closest view -and Allah knows best- is that it is a bribe so that he does not buy from anyone but him. The agent should leave this, and be trustworthy, staying away from these things that may harm him, and may lead him to betrayal. We ask Allah for safety. Yes.

The presenter: O Allah, amen.