1 Samuel 17:46-50
English Standard Version
Chapter 17
46This day the Lord will deliver you into my hand, and I will strike you down and cut off your head. And I will give the dead bodies of the host of the Philistines this day to the birds of the air and to the wild beasts of the earth, that all the earth may know that there is a God in Israel, 47and that all this assembly may know that the Lord saves not with sword and spear. For the battle is the Lord 's, and he will give you into our hand."
48When the Philistine arose and came and drew near to meet David, David ran quickly toward the battle line to meet the Philistine.
49And David put his hand in his bag and took out a stone and slung it and struck the Philistine on his forehead. The stone sank into his forehead, and he fell on his face to the ground.