The reason for David's presence at the battle 17:12-25

At this time in his life David was assisting Saul as his armorbearer when he was not tending his father's sheep (v. 15). Moses too had been tending sheep before God called him to shepherd His people Israel (Exod. 3:1). The site of battle was 15 miles due west of David's hometown, Bethlehem. The Old Testament sometimes used "Ephratah"(v. 12), an older name for Bethlehem, to distinguish the Bethlehem in Judah from the one in Zebulon. David journeyed to the battle site to bring food (including cheeseburgers? v. 18) to his brothers and their fellow soldiers and to collect news to bring back to his father.¹⁸⁵Little did Jesse expect that the news David would bring back home was that he had slain Goliath and that the Israelites had routed the Philistines. The battle had been a stand-off for 40 days (v. 16). The number 40 often represents a period of testing in the Bible (cf. the Israelites' testing in the wilderness for 40 years, Jesus' testing for 40 days, etc.). This was another test for Israel. Would the nation trust in the arm of the flesh or in God?

Part of the reward for defeating Goliath that Saul had promised was that the victor's family would be tax free in Israel (v. 25).¹⁸⁶The giving of the leader's daughter in marriage to a valiant warrior was not without precedent in Israel (cf. Caleb's challenge in Josh. 15:16).