Is it permissible to work secretly (off the books) without the knowledge of a Western country that pays a Muslim a monthly salary, with the aim of saving money to move to an Arab country in the future?

The country that sheltered the questioner and granted him a monthly allowance, stipulating that he not work without its knowledge—this is a condition that must be fulfilled, based on the Prophet’s (peace be upon him) saying: "Muslims are bound by their conditions." If a person performs a permissible job, he is sinful for violating the condition, unless he is compelled to do so, and there is no necessity in what was mentioned.