1 Samuel 17:34-36

But David told him: Your Majesty, I take care of my father's sheep. And when one of them is dragged off by a lion or a bear, I go after it and beat the wild animal until it lets the sheep go. If the wild animal turns and attacks me, I grab it by the throat and kill it. Sir, I have killed lions and bears that way, and I can kill this worthless Philistine. He shouldn't have made fun of the army of the living God!