What is the legal ruling on an employee colluding with a vendor to quote a price higher than the actual price to the company, so that the employee can take the difference, knowing that the company would not approve if it found out?

Engaging in this behavior is forbidden due to its containing Sharia violations such as lying, treachery, and unlawfully taking people's money. The perpetrator must repent, seek forgiveness, abandon this behavior, regret what has passed, resolve not to return to it, and then return all excess money beyond the true price to the company.