1 Samuel 17:19 (KJV)

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 to thy brethren;

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

Now Saul, and they, and all the men of Israel, were in the valley of Elah, fighting with the Philistines.

And David rose up early in the morning, and left the sheep with a keeper, and took, and went, as Jesse had commanded him; and he came to the trench, as the host was going forth to the fight, and shouted for the battle.

For Israel and the Philistines had put the battle in array, army against army.