I Samuel 17:26-33

Then David spoke to the men who stood by him, saying, “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?” And the people answered him in this manner, saying, “So shall it be done for the man who kills him.” Now Eliab his oldest brother heard when he spoke to the men; and Eliab’s anger was aroused against David, and he said, “Why did you come down here? And with whom have you left those few sheep in the wilderness? I know your pride and the insolence of your heart, for you have come down to see the battle.” And David said, “What have I done now? Is there not a cause?” Then he turned from him toward another and said the same thing; and these people answered him as the first ones did. Now when the words which David spoke were heard, they reported them to Saul; and he sent for him. Then David said to Saul, “Let no man’s heart fail because of him; your servant will go and fight with this Philistine.” And Saul said to David, “You are not able to go against this Philistine to fight with him; for you are a youth, and he a man of war from his youth.”