What is the ruling on a maintenance company manager who subcontracts with other companies and takes a commission from them without the knowledge of the company owner?

The manager is an employee and an agent for the company owner, and he is not permitted to act except within what his principal has authorized him to do. It is not lawful for the manager to take any commission for himself without the employer's knowledge and permission, because this could lead to harming the company he works for, in terms of price and quality of goods.