Jamieson, Fausset and Brown on 1 Samuel 17:42-47

42-47. the Philistine said ... said David to the Philistine--When the two champions met, they generally made each of them a speech, and sometimes recited some verses, filled with allusions and epithets of the most opprobrious kind, hurling contempt and defiance at one another. This kind of abusive dialogue is common among the Arab combatants still. David's speech, however, presents a striking contrast to the usual strain of these invectives. It was full of pious trust, and to God he ascribed all the glory of the triumph he anticipated.