1 Samuel 17:13 (KJV)

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.

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 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 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.

And Jesse said unto David his son, Take now for thy brethren an ephah of this parched corn, and these ten loaves, and run to the camp of thy brethren;

And carry these ten cheeses unto the captain of their thousand, and look how thy brethren fare, and take their pledge.