1 Samuel 17:9-13

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.

When Saul and all Israel heard those words of the Philistine, they were dismayed, and greatly afraid.

Now David was the son of that Ephrathite of Beth-lehem-judah, 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.