"Those who use rewards must be trustworthy, and those who use punishment must be loyal" refers to the thinking of the military school, which means: rewards are important in keeping one's word, and punishments are important in resolute execution. This sentence comes from "Six Taoists, Wen Tao, Rewards and Punishments", and is known as the ancestor of military strategy.
Examples of "reward":
1. Please remember that rewards will never be the goal we work and strive for.
2. The greatest reward is to give you the opportunity to work, and the greatest favor is to constantly provide you with opportunities to perform.
3. Happiness is not a reward, but a result; suffering is not a punishment, but a retribution.