1 Samuel 17:47-51

and that all this assembly may know that the LORD does not deliver by sword or by spear; for the battle is the LORD’S and He will give you into our hands.” Then it happened when the Philistine rose and came and drew near to meet David, that David ran quickly toward the battle line to meet the Philistine. And David put his hand into his bag and took from it a stone and slung it, and struck the Philistine on his forehead. And the stone sank into his forehead, so that he fell on his face to the ground. Thus David prevailed over the Philistine with a sling and a stone, and he struck the Philistine and killed him; but there was no sword in David’s hand. Then David ran and stood over the Philistine and took his sword and drew it out of its sheath and killed him, and cut off his head with it. When the Philistines saw that their champion was dead, they fled.