1 Samuel 17:26-37

Then David spoke to the men who were standing by him, “What will be done for the man who kills this Philistine and removes the disgrace [of his taunting] from Israel? For who is this uncircumcised Philistine that he has taunted and defied the armies of the living God?” The men told him, “That is what will be done for the man who kills him.” Now Eliab his oldest brother heard what he said to the men; and Eliab’s anger burned against David and he said, “Why have you come down here? With whom did you leave those few sheep in the wilderness? I know your presumption (overconfidence) and the evil of your heart; for you have come down in order to see the battle.” But David said, “What have I done now? Was it not just a [harmless] question?” Then David turned away from Eliab to someone else and asked the same question; and the people gave him the same answer as the first time. When the words that David spoke were heard, the men reported them to Saul, and he sent for him. David said to Saul, “Let no man’s courage fail because of him (Goliath). Your servant will go out and fight with this Philistine.” Then Saul said to David, “You are not able to go against this Philistine to fight him. For you are [only] a young man and he has been a warrior since his youth.” But David said to Saul, “Your servant was tending his father’s sheep. When a lion or a bear came and took a lamb out of the flock, I went out after it and attacked it and rescued the lamb from its mouth; and when it rose up against me, I seized it by its whiskers and struck and killed it. Your servant has killed both the lion and the bear; and this uncircumcised Philistine will be like one of them, since he has taunted and defied the armies of the living God.” David said, “The LORD who rescued me from the paw of the lion and from the paw of the bear, He will rescue me from the hand of this Philistine.” And Saul said to David, “Go, and may the LORD be with you.”