1 Samuel 17:17-30
Jesse said to his son David, "Take for your brothers an ephah of this parched grain and these ten loaves, and carry them quickly to the camp to your brothers; also take these ten cheeses to the commander of their thousand. See how your brothers fare, and bring some token from them."
Now Saul, and they, and all the men of Israel, were in the valley of Elah, fighting with the Philistines. David rose early in the morning, left the sheep with a keeper, took the provisions, and went as Jesse had commanded him. He came to the encampment as the army was going forth to the battle line, shouting the war cry. Israel and the Philistines drew up for battle, army against army. David left the things in charge of the keeper of the baggage, ran to the ranks, and went and greeted his brothers. As he talked with them, the champion, the Philistine of Gath, Goliath by name, came up out of the ranks of the Philistines, and spoke the same words as before. And David heard him.
All the Israelites, when they saw the man, fled from him and were very much afraid. The Israelites said, "Have you seen this man who has come up? Surely he has come up to defy Israel. The king will greatly enrich the man who kills him, and will give him his daughter and make his family free in Israel." David said to the men who stood by him, "What shall be done for the man who kills this Philistine, and takes away the reproach from Israel? For who is this uncircumcised Philistine that he should defy the armies of the living God?" The people answered him in the same way, "So shall it be done for the man who kills him."
His eldest brother Eliab heard him talking to the men; and Eliab's anger was kindled against David. He said, "Why have you come down? With whom have you left those few sheep in the wilderness? I know your presumption and the evil of your heart; for you have come down just to see the battle." David said, "What have I done now? It was only a question." He turned away from him toward another and spoke in the same way; and the people answered him again as before.