1 Samuel 17:32-36

And David said to Saul, Let no man’s heart fail because of him; thy servant will go and fight with this Philistine. And Saul said to David, Thou art not able to go against this Philistine to fight with him; for thou art but a youth, and he a man of war from his youth. And David said unto Saul, Thy servant was keeping his father’s sheep; and when there came a lion, or a bear, and took a lamb out of the flock, I went out after him, and smote him, and delivered it out of his mouth; and when he arose against me, I caught him by his beard, and smote him, and slew him. Thy servant smote both the lion and the bear: and this uncircumcised Philistine shall be as one of them, seeing he hath defied the armies of the living God.