1 Samuel 17:48-52

When the Philistine drew nearer to meet David, David ran quickly toward the battle line to meet the Philistine. David put his hand in his bag, took out a stone, slung it, and struck the Philistine on his forehead; the stone sank into his forehead, and he fell face down on the ground. So David prevailed over the Philistine with a sling and a stone, striking down the Philistine and killing him; there was no sword in David's hand. Then David ran and stood over the Philistine; he grasped his sword, drew it out of its sheath, and killed him; then he cut off his head with it. When the Philistines saw that their champion was dead, they fled. The troops of Israel and Judah rose up with a shout and pursued the Philistines as far as Gath and the gates of Ekron, so that the wounded Philistines fell on the way from Shaaraim as far as Gath and Ekron.