One Piece Chapter 3, page 19-20: Chapter 3: Enter Zolo: Pirate Hunter

An adult woman sits with them, explaining that Captain Morgan and Helmeppo are the real villains who execute people for no reason. Suddenly, Helmeppo struts through the town street, demanding that citizens bow lower. He loudly boasts that they will hold a public execution for Zolo in three days to make an example of him. Luffy is shocked, remembering Zolo's belief in the one-month promise. When confronted, Helmeppo laughs and dismisses the promise as a joke, calling Zolo a stupid beast for believing it.

Enraged by Helmeppo's cruel deception, Luffy punches Helmeppo squarely in the face, sending him flying. Koby desperately tries to hold Luffy back, warning him that attacking Helmeppo means making an enemy of the Navy. But Luffy, completely determined, declares that he has made his decision: he is going to ask Zolo to join his crew.