48 Now when the Philistine made a move and came near to David, David quickly went at a run in the direction of the army, meeting the Philistine face to face. 49 And David put his hand in his bag and took out a stone and sent it from his leather band straight at the Philistine, and the stone went deep into his brow, and he went down to the earth, falling on his face. 50 So David overcame the Philistine with his leather band and a stone, wounding the Philistine and causing his death: but David had no sword in his hand. 51 So running up to the Philistine and putting his foot on him, David took his sword out of its cover, and put him to death, cutting off his head with it. And when the Philistines saw that their fighter was dead, they went in flight.
Matthew Henry's Commentary on 1 Samuel 17:48-51
Commentary on 1 Samuel 17:48-58
(Read 1 Samuel 17:48-58)
See how frail and uncertain life is, even when a man thinks himself best fortified; how quickly, how easily, and by how small a matter, the passage may be opened for life to go out, and death to enter! Let not the strong man glory in his strength, nor the armed man in his armour. God resists the proud, and pours contempt on those who defy him and his people. No one ever hardened his heart against God and prospered. The history is recorded, that all may exert themselves for the honour of God, and the support of his cause, with bold and unshaken reliance on him. There is one conflict in which all the followers of the Lamb are, and must be engaged; one enemy, more formidable than Goliath, still challenges the armies of Israel. But "resist the devil, and he will flee from you." Go forth to battle with the faith of David, and the powers of darkness shall not stand against you. But how often is the Christian foiled through an evil heart of unbelief!