Is it permissible to secretly take financial dues from an employer without his knowledge, in exchange for unpaid overtime hours, which he claims are part of the obligatory work?

Both the employer and the employee must adhere to the limits set by Allah and fulfill each other's rights. The worker must complete his work fully, and the employer must pay his wages in full. The contract concluded between them governs their rights. If labor regulations stipulate extra pay for overtime work, the employer must pay it. If he refuses, the employee is permitted to take it without his knowledge. However, if the regulations do not require compensation for overtime, then it is not permissible to take anything in exchange for work that was not agreed upon beforehand.