Is a Muslim obligated to speak the truth to the manager at work, whatever the consequences?

A Muslim must enjoin good and forbid evil according to his ability, as Allah Almighty says: "So fear Allah as much as you are able." The obligation is lifted from him if he is exposed to clear harm he cannot bear, or great injury he cannot endure, for the Prophet, peace and blessings be upon him, said: "A believer should not humble himself." It was asked: "How does he humble himself?" He replied: "By exposing himself to affliction he cannot bear." In such a case, he is obligated to detest the evil in his heart, for the Prophet, peace and blessings be upon him, said: "Whoever among you sees an evil, let him change it with his hand; if he cannot, then with his tongue; if he cannot, then with his heart—and that is the weakest of faith."