1st Samuel 17:1-54
The Israelites and the Philistines were now at war. The two armies were posted on two mountains, with a valley between them.
A giant, named Goliath of Gath, came out of the camp of the Philistines, and challenged any one of the Israelites to come and fight him. If he killed the Israelite, then the Israelites were to serve the Philistines, if the Israelite killed him, then the Philistines would serve them.
Goliath was a huge giant, nine or ten feet high and was covered from head to foot in heavy brazen armor. The staff of his spear was very thick. For forty days this terrible giant came out, defying all the Israelites. Even Saul, the king, who was a brave man, was afraid of him.
The three eldest sons of Jesse were in Saul's army; and their father told David, who was tending his sheep at Bethlehem to go to the camp with some parched corn, and bread for his brothers. He arrived there just as the two armies were advancing to battle. He was talking to his brothers when out came Goliath the giant, defying the Israelites, who ran away at the very sight of him.
David was angry seeing the armies of God's chosen people being mocked and taunted by a heathen. He asked those around him what should be done for the man who killed him. They told him that he would have honors and riches, and that he would marry the king's daughter.
Saul, heard what David had said and sent for him. David told the king that he would go and fight the giant.
Saul reminded him that he was very young, and that the Philistine had been a soldier all his life. David answered that he had killed a lion and a bear that had attacked his flock, and he knew that God would also help him to kill this great giant.
Saul agreed to allow David to fight Goliath. He gave him armor and a sword, but David refused them. He took only his staff and sling, with five smooth stones in his shepherd's bag, and went to meet the giant, who came on cursing and taunting him.
David, ran forward, took a stone from his bag, and slang it at the giant, whom it struck in the forehead! The great giant Goliath fell on his face to the ground, and David cut off his head with his own sword.
The Philistines took to flight when they saw that the giant was dead.