A shepherd boy faces a giant in the name of the LORD of hosts.
The story
While Israel's army trembles, young David hears the giant's defiance and will not be silent. Refusing Saul's armour, he takes five smooth stones and a sling. "The battle is the LORD's," he declares, and Goliath falls.
What it teaches
The size of the giant matters less than the greatness of God.
In the Scriptures
David said moreover, The LORD that delivered me out of the paw of the lion, and out of the paw of the bear, he will deliver me out of the hand of this Philistine. And Saul said unto David, Go, and the LORD be with thee. 1 Samuel 17:37 · KJV
Then said David to the Philistine, Thou comest to me with a sword, and with a spear, and with a shield: but I come to thee in the name of the LORD of hosts, the God of the armies of Israel, whom thou hast defied. This day will the LORD deliver thee into mine hand; and I will smite thee, and take thine head from thee; and I will give the carcases of the host of the Philistines this day unto the fowls of the air, and to the wild beasts of the earth; that all the earth may know that there is a God in Israel. And all this assembly shall know that the LORD saveth not with sword and spear: for the battle is the LORD’s, and he will give you into our hands. 1 Samuel 17:45-47 · KJV