1 Samuel 17:45-50

But David replied to the Philistine, “You are coming against me with sword and spear and javelin. But I am coming against you in the name of the LORD of hosts, the God of Israel’s armies, whom you have defied! This very day the LORD will deliver you into my hand! I will strike you down and cut off your head. This day I will give the corpses of the Philistine army to the birds of the sky and the wild animals of the land. Then all the land will realize that Israel has a God and all this assembly will know that it is not by sword or spear that the LORD saves! For the battle is the LORD’s, and he will deliver you into our hand.” The Philistine drew steadily closer to David to attack him, while David quickly ran toward the battle line to attack the Philistine. David reached his hand into the bag and took out a stone. He slung it, striking the Philistine on the forehead. The stone sank deeply into his forehead, and he fell down with his face to the ground. David prevailed over the Philistine with just the sling and the stone. He struck down the Philistine and killed him. David did not even have a sword in his hand.