1 Samuel 17:47-51

And everyone assembled here will know that the LORD rescues his people, but not with sword and spear. This is the LORD’s battle, and he will give you to us!” As Goliath moved closer to attack, David quickly ran out to meet him. Reaching into his shepherd’s bag and taking out a stone, he hurled it with his sling and hit the Philistine in the forehead. The stone sank in, and Goliath stumbled and fell face down on the ground. So David triumphed over the Philistine with only a sling and a stone, for he had no sword. Then David ran over and pulled Goliath’s sword from its sheath. David used it to kill him and cut off his head.