1 Samuel 17:6-16

6 On his legs he had bronze shin guards and on his back a bronze javelin.
7 The shaft of his spear was like the beam used by weavers. The head of his spear was made of 15 pounds of iron. The man who carried his shield walked ahead of him.
8 Goliath stood and called to the Israelites, "Why do you form a battle line? Am I not a Philistine, and aren't you Saul's servants? Choose a man, and let him come down to [fight] me.
9 If he can fight me and kill me, then we will be your slaves. But if I overpower him and kill him, then you will be our slaves and serve us."
10 The Philistine added, "I challenge the Israelite battle line today. Send out a man so that we can fight each other."
11 When Saul and all the Israelites heard what this Philistine said, they were gripped with fear.
12 David was a son of a man named Jesse from the region of Ephrath and the city of Bethlehem in Judah. Jesse had eight sons, and in Saul's day he was an old man.
13 Jesse's three oldest sons joined Saul's army for the battle. The firstborn was Eliab, the second was Abinadab, the third was Shammah,
14 and David was the youngest. The three oldest joined Saul's army.
15 David went back and forth from Saul's camp to Bethlehem, where he tended his father's flock.
16 Each morning and evening for 40 days, the Philistine came forward and made his challenge.