One Piece Chapter 4, page 5: Chapter 4: The Great Captain Morgan

Zoro explains that he has his own mission and refuses to become a "stinking pirate." Luffy questions if he thinks he's too good to be a pirate, pointing out that everyone already thinks Zoro is a demon bounty hunter. Zoro firmly states, "I live by my own code... I've never done anything I regret, and I don't intend to in the future. I don't care what people think. Which is why I'll never be a pirate!!" Luffy mentions he heard Zoro can use a sword, and Zoro boasts, "Hmph! If I wasn't tied up, I'd show you..." Luffy stubbornly declares, "Sorry, but I've made up my mind! You're gonna join my crew!!" Zoro screams back, "I don't care what you've decided!!"