One of Machiavelli’s advices to all leaders is to be careful who you trust. Machiavelli states: "... He who is the cause of another becoming powerful is ruined; because that predominance has been brought about by astuteness or else by force, and both are distrusted by him who has been raised to power" (229-33).
It is proven all over the history that treason comes from people who were most trusted by their leaders. On the other side some people say that a strong rule is build by the loyalty and trust between the rulers and the people, but here is another opinion from Colett:
Employees do change masters willingly, a new executive should not be concerned over the loyalty of staff, as some believe. Pandolfo Petrucci, prince of Sienna, governed his state more by those he suspected than by others. Employees who are regarded with suspicion at first may prove more useful later than those receiving early confidences. Why? Because they know that by their deeds they must cancel bad opinions previously held of them (XX). If, however, employees are aloof, and careful observation discloses this is due not to personal pride, natural lack of courage, or caution in accepting a new leader, but to secret plotting, the executive must make sure that their expressions or acts are not contrary to personal best interests (IX). So leaders have to be aware of their retinue. They should not choose their retinue just because they trust them, but there should be another bases, as quoted, suspicion makes people more careful about their positions and also makes them strive to achieve their leader’s satisfaction.