1 Samuel 17:48-52

Then it happened, when the Philistine came closer 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 penetrated his forehead, and he fell on his face to the ground.

So David prevailed over the Philistine with the sling and the stone: he struck the Philistine and killed him, and 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 finished him, and cut off his head with it. When the Philistines saw that their champion was dead, they fled.

Then the men of Israel and Judah rose up and shouted, and they pursued the Philistines as far as the valley, and to the gates of Ekron. And the Philistine dead lay along the way to Shaaraim, even to Gath and Ekron.