1 Samuel 17:47-51

All those gathered here will know that it is not by sword or spear that the LORD saves; for the battle is the LORD’s, and he will give all of you into our hands.” As the Philistine moved closer to attack him, David ran quickly toward the battle line to meet him. Reaching into his bag and taking out a stone, he slung it and struck the Philistine on the forehead. The stone sank into his forehead, and he fell facedown on the ground. So David triumphed over the Philistine with a sling and a stone; without a sword in his hand he struck down the Philistine and killed him. David ran and stood over him. He took hold of the Philistine’s sword and drew it from the sheath. After he killed him, he cut off his head with the sword. When the Philistines saw that their hero was dead, they turned and ran.