One Piece Chapter 6, page 5-6: Chapter 6: Number One

Zoro addresses Luffy while keeping his swords ready, saying, "ALL RIGHT, SO I'M A PIRATE. I GAVE YOU MY WORD. I'VE FOUGHT THE NAVY, THEREFORE I'M OFFICIALLY AN OUTLAW... BUT, HEAR THIS!! I HAVE A MISSION TO FULFILL!!!" He looks directly at Luffy with fierce determination and declares, "I'M GOING TO BE THE WORLD'S GREATEST SWORDSMAN! ALL I HAVE LEFT IS MY DESTINY! MY NAME MAY BE INFAMOUS... BUT IT'S GONNA SHAKE THE WORLD!!!" He then adds a stern warning: "BUT YOU ARE MAKING ME BECOME A PIRATE! SO IF I HAVE TO ABANDON MY DREAM FOR ANY REASON......THEN I'M GOING TO MAKE YOU COMMIT HARA KIRI!!!

Luffy beams with a massive grin, completely unfazed by Zoro's threat. He replies, "THE WORLD'S GREATEST SWORDSMAN, THAT'S GREAT! AND IT'S FITTING SINCE YOUR NEW BOSS IS GOING TO BE THE KING OF THE PIRATES! ANYTHING ELSE WOULD MAKE ME LOOK BAD!" Zoro can only smirk and mutter, "HMPH! YOU TALK BIG..." Meanwhile, Captain Morgan loses his patience and screams at his hesitant troops, "WHY DO YOU HESITATE!? HACK THOSE BRIGANDS INTO MINCE-MEAT! NOW!!" Sensing the incoming attack, Luffy prepares his own move, shouting, "GUM-GUM..." and warning his new partner, "ZOLO, DUCK!!