Falstaff: But to say I know more harm in him than in myself were to say more than I know. That he is old, the more the pity, his white hairs do witness it. But that he is, saving your reverence, a whoremaster, that I utterly deny. If sack and sugar be a fault, God help the wicked. If to be old and merry be a sin, then many an old host that I know is damned. If to be fat be to be hated, then Pharaoh’s lean kine are to be loved. No, my good lord, banish Peto, banish Bardolph, banish Poins, but for sweet Jack Falstaff, kind Jack Falstaff, true Jack Falstaff, valiant Jack Falstaff, and therefore more valiant being, as he is, old Jack Falstaff,
Banish not him thy Harry’s company,
Banish not him thy Harry’s company.
Banish plump Jack, and banish all the world.
Prince: I do; I will.
(Act 2, Scene 4, lines 425–439)

This exchange occurs during Harry and Falstaff’s game of role—playing, as Falstaff pretends to be Harry so that Harry can prepare for his upcoming meeting with his father. Falstaff uses his time in the role of King Henry mainly to praise himself, urging Harry to keep Falstaff near him—something that the real king would never do, but certainly in keeping with Falstaff’s character. Playing Harry, Falstaff lists his own faults, and then excuses each of them—“If sack and sugar be a fault, God help the wicked. If to be old and merry be a sin, then many and old host that I know is damned”—and then, improbably, begins to list his own supposed virtues, calling himself “sweet,” “kind,” “true,” and “valiant.” Falstaff is not sweet, kind, true, or valiant, but his constant claims to be these things are part of what makes him endearing. In any case, this speech is important because it lets us in on some of the complexities of Harry and Falstaff’s relationship. Falstaff understands that he is undesirable company for Harry and worries that Harry will one day break his ties with him. So, in the role of King Henry, Falstaff urges Harry not to do so. Harry’s icy reply, “I do; I will,” foreshadows the moment of the actual break in the next play, Henry IV, Part 2.