1 Samuel 17:49-50

And David put his hand in his bag, and took thence a stone, and slang it, and smote the Philistine in his forehead; and the stone sank into his forehead, and he fell upon his face to the earth. So David prevailed over the Philistine with a sling and with a stone, and smote the Philistine, and slew him; but there was no sword in the hand of David.