Is it permissible to refrain from changing an evil with the tongue and be content with changing it with the heart to avoid the harm of being fired from work, and would one then be sinful?

Enjoining good and forbidding evil is obligatory, with different levels: by hand, and if unable, then by tongue, and if unable, then by heart, which is the weakest of faith. If a Muslim is unable to forbid evil with his hand or tongue due to unbearable harm or a greater corruption, he is excused and moves to forbidding it with his heart, and there is no sin upon him. If the questioner would lose his job and consequently face ruin or the ruin of his family whom he supports, he is excused in contenting himself with forbidding it by heart. However, if the dismissal is an illusion or a weak assumption, or if he is able to do without the job or find another, then he cannot content himself with forbidding it by heart.