19 There wasn't a blacksmith to be found anywhere in Israel. The Philistines made sure of that - "Lest those Hebrews start making swords and spears." 20 That meant that the Israelites had to go down among the Philistines to keep their farm tools - plowshares and mattocks, axes and sickles - sharp and in good repair. 21 They charged a silver coin for the plowshares and mattocks, and half that for the rest. 22 So when the battle of Micmash was joined, there wasn't a sword or spear to be found anywhere in Israel - except for Saul and his son Jonathan; they were both well-armed.
Matthew Henry's Commentary on 1 Samuel 13:19-22
Commentary on 1 Samuel 13:15-23
(Read 1 Samuel 13:15-23)
See how politic the Philistines were when they had power; they not only prevented the people of Israel from making weapons of war, but obliged them to depend upon their enemies, even for instruments of husbandry. How impolitic Saul was, who did not, in the beginning of his reign, set himself to redress this. Want of true sense always accompanies want of grace. Sins which appear to us very little, have dangerous consequences. Miserable is a guilty, defenceless nation; much more those who are destitute of the whole armour of God.