What is the ruling on a government employee investing his private money in a project to improve his financial situation for marriage, if the law prohibits establishing businesses in parallel with the job, and is the money earned from this project lawful (halal)?

A government employee is a private hire (ajir khass); it is not permissible for him to work another job during official working hours. However, it is permissible for him to do so outside of these hours, unless it was stipulated to him that he should not work and he accepted this condition. In such a case, he is obligated to fulfill the condition, based on the Prophet's (peace be upon him) saying: "Muslims are bound by their conditions." His earnings are lawful as long as his work is lawful. He incurs sin for violating the aforementioned condition in the contract. If he obtains permission from the authorized official, then it is permissible for him to work.