Chapter 19 discusses how the prince is to avoid hatred and contempt. Above all, Machiavelli emphasizes the need to conceal the arbitrary character of executive power.
What makes him contemptible is to be held variable, light, effeminate, pusillanimous, irresolute, from which a prince should guard himself as from a shoal. He should contrive that greatness, spiritedness, gravity, and strength are recognized in his actions, and he should insist that his judgments in the private concerns of his subjects be irrevocable.
Resolution or resoluteness is necessary for good government. To waffle, to flip-flop, to decide one way today only to reverse yourself tomorrow simply undermines the people’s confidence in your capacity to rule, which is coterminous with your capacity for decision.
As Machiavelli will emphasize later in Chapter 23, being agreeable will make one inconstant, thus it is better to be hard. Think back to Shakespeare’s Julius Caesar.