1 Samuel 17:48-49

When the Philistine arose. Apparently he was seated, as was the rule with armies in ancient times when not engaged in conflict. When, then, he saw David emerge from the ravine, he rose, and, carrying his vast load of armour, moved slowly towards his enemy, trying to frighten him by his curses. David, meanwhile, in his light equipment, ran towards the army, Hebrew, "the rank," i.e. the Philistine line, in front of which Goliath had been sitting. As the giant's helmet had no visor, that protection not having as yet been invented, and his shield was still carried by his armour bearer, his face was exposed to David's missiles. And in those days, before firearms were invented, men by constant practice "could sling stones at a hair-breadth, and not miss" ( 20:16 ). And even if David were not quite as skilful as those Benjamites, yet, as the giant could move only very slowly, the chances were that he would hit him with one or more of his five pebbles. As it was, he struck him at his first attempt upon the forehead with such force that Goliath was stunned, and fell down upon his face to the ground.