1 Samuel 17:38-50

Then Saul dressed David in his garments and put a bronze helmet on his head, and put a coat of mail (armor) on him. Then David fastened his sword over his armor and tried to walk, [but he could not,] because he was not used to them. And David said to Saul, “I cannot go with these, because I am not used to them.” So David took them off. Then he took his [shepherd’s] staff in his hand and chose for himself five smooth stones out of the stream bed, and put them in his shepherd’s bag which he had, that is, in his shepherd’s pouch. With his sling in his hand, he approached the Philistine. The Philistine came and approached David, with his shield-bearer in front of him. When the Philistine looked around and saw David, he derided and disparaged him because he was [just] a young man, with a ruddy complexion, and a handsome appearance. The Philistine said to David, “Am I a dog, that you come to me with [shepherd’s] staffs?” And the Philistine cursed David by his gods. The Philistine also said to David, “Come to me, and I will give your flesh to the birds of the sky and the beasts of the field.” Then David said to the Philistine, “You come to me with a sword, a spear, and a javelin, but I come to you in the name of the LORD of hosts, the God of the armies of Israel, whom you have taunted. This day the LORD will hand you over to me, and I will strike you down and cut off your head. And I will give the corpses of the army of the Philistines this day to the birds of the sky and the wild beasts of the earth, so that all the earth may know that there is a God in Israel, and that this entire assembly may know that the LORD does not save with the sword or with the spear; for the battle is the LORD’S and He will hand you over to us.” When the Philistine rose and came forward to meet David, David ran quickly toward the battle line to meet the Philistine. David put his hand into his bag and took out a stone and slung it, and it struck the Philistine on his forehead. The stone penetrated his forehead, and he fell face down on the ground. So David triumphed over the Philistine with a sling and a stone, and he struck down the Philistine and killed him; but there was no sword in David’s hand.