One Piece Chapter 3, page 16: Chapter 3: Enter Zolo: Pirate Hunter

Zolo explains that he doesn't need Luffy's help because he has his own plans and will be freed after surviving the month, as promised by Helmeppo. Luffy is skeptical about surviving a month without food, but Zolo boasts about his superior willpower and tells Luffy to look elsewhere. As Luffy turns to leave, Zolo calls him back, asking him to pick up something from the ground.