Is it permissible for an employee to work outside his official workplace on personal tasks belonging to the Chairman of the Board of Directors, while his administrative affiliation and salary remain with the company?

If the chairman of the company's board of directors is authorized by its articles of association to do so, then there is no harm in performing a permissible job outside the company and receiving a salary for it. However, if he is not authorized, it is not permissible to receive a salary from the company for work that is unrelated to it. The administration's payment of such a salary does not absolve one of sin if it violates the company's articles of association.