What is the ruling on working more than one job without the employer's agreement, and taking a percentage of the profits from verbally agreed-upon deals? Is it permissible to give employees additional pay without the employer's knowledge, and what is the ruling on taking money for additional work without the employer's knowledge?

For a private employee (salaried worker), it is permissible to refuse additional work outside or during official working hours, unless there is a condition or a custom to the contrary. They have the right to request payment for such work. This is similar to the jurists' view regarding a shepherd who is not obligated to herd sheep born after the hiring contract, unless there is a condition or a custom.

If the agreement is based on a percentage of profits, this is a "ju'alah" (a stipulated reward for performing a task), and you are entitled to it if you achieve the profits and fulfill the terms of the ju'alah. As for past work, if the person in charge denies your right, previous fatwas have clarified the scholars' opinions on this matter.

Regarding the future, you may either abstain from non-obligatory work, or perform it voluntarily if the employer is unwilling to pay for it. It is not permissible to take payment for it secretly. As for the employees under your supervision, you should compensate them for overtime work according to the company's established regulations.