1 Samuel 17:16-20

And the Philistine came forward morning and evening, and took his stand for forty days.

Then Jesse said to his son David, “Take now for your brothers an ephah of this roasted grain and these ten loaves, and run to the camp to your brothers.

Bring also these ten slices of cheese to the commander of their thousand, and look into the well-being of your brothers and bring back confirmation from them.

For Saul and they and all the men of Israel are in the Valley of Elah, fighting the Philistines.” David Accepts the Challenge

So David got up early in the morning and left the flock with a keeper, and took the supplies and went as Jesse had commanded him. And he came to the entrenchment encircling the camp while the army was going out in battle formation, shouting the war cry.