One Piece Chapter 1, page 47: Romance Dawn

Shanks floats in the quiet water, holding Luffy. He says gently: "Luffy, I'm sorry. Makino told me what happened. You stood up for me." Luffy begins to sob uncontrollably: "Shanks!!! B-but..." Shanks smiles warmly: "Hey, stop crying! You're a tough guy, remember?" Luffy looks up, crying hysterically: "WHAT ABOUT YOUR ARM!!?" Shanks' left arm has been completely bitten off, bleeding heavily into the sea.