1 Samuel 17:48-51

48Then it happened when the Philistine rose and came and drew near to meet David, that 1David ran quickly toward the battle line to meet the Philistine. 49And 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.

50Thus 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. 51Then David ran and stood over the Philistine and 2took his sword and drew it out of its sheath and killed him, and cut off his head with it. 3When the Philistines saw that their champion was dead, they fled.