1 Samuel 17:42

38 Then Saul clothed David in his own tunic, put a bronze helmet on his head, and dressed him in armor.

39 David strapped his sword over the tunic and tried to walk, but he was not accustomed to them. “I cannot walk in these,” David said to Saul. “I am not accustomed to them.” So David took them off.

40 And David took his staff in his hand, selected five smooth stones from the brook, and put them in the pouch of his shepherd’s bag. And with his sling in hand, he approached the Philistine.

41 Now the Philistine came closer and closer to David, with his shield-bearer before him.

42 When the Philistine looked and saw David, he despised him because he was just a boy, ruddy and handsome.

43 “Am I a dog,” he said to David, “that you come at me with sticks?” And the Philistine cursed David by his gods.

44 “Come here,” he called to David, “and I will give your flesh to the birds of the air and the beasts of the field!”

45 But David said to the Philistine, “You come against me with sword and spear and javelin, but I come against you in the name of the LORD of Hosts, the God of the armies of Israel, whom you have defied.

46 This day the LORD will deliver you into my hand. This day I will strike you down, cut off your head, and give the carcasses of the Philistines to the birds of the air and the creatures of the earth. Then the whole world will know that there is a God in Israel.

Read all of 1 Samuel 17