1 Samuel 17:11 (KJV)

And he had greaves of brass upon his legs, and a target of brass between his shoulders.

And the staff of his spear was like a weaver's beam; and his spear's head weighed six hundred shekels of iron: and one bearing a shield went before him.

And he stood and cried unto the armies of Israel, and said unto them, Why are ye come out to set your battle in array? am not I a Philistine, and ye servants to Saul? choose you a man for you, and let him come down to me.

If he be able to fight with me, and to kill me, then will we be your servants: but if I prevail against him, and kill him, then shall ye be our servants, and serve us.

And the Philistine said, I defy the armies of Israel this day; give me a man, that we may fight together.

Now David was the son of that Ephrathite of Bethlehemjudah, whose name was Jesse; and he had eight sons: and the man went among men for an old man in the days of Saul.

And the three eldest sons of Jesse went and followed Saul to the battle: and the names of his three sons that went to the battle were Eliab the firstborn, and next unto him Abinadab, and the third Shammah.

And David was the youngest: and the three eldest followed Saul.

But David went and returned from Saul to feed his father's sheep at Bethlehem.

And the Philistine drew near morning and evening, and presented himself forty days.