1 Samuel 17:32-37, 45

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. And David said, Jehovah that delivered me out of the paw of the lion, and out of the paw of the bear, he will deliver me out of the hand of this Philistine. And Saul said unto David, Go, and Jehovah shall be with thee.

Then said David to the Philistine, Thou comest to me with a sword, and with a spear, and with a javelin: but I come to thee in the name of Jehovah of hosts, the God of the armies of Israel, whom thou hast defied.