We are not told wherein it was that the people of Israel offended God, so as to forfeit his presence and turn his hand against them, as Samuel had threatened (Sa1 12:15); but doubtless they left God, else he would not have left them, as here it appears he did; for,
I. Saul was very weak and impolitic, and did not order his affairs with discretion. Saul was the son of one year (so the first words are in the original), a phrase which we make to signify the date of his reign, but ordinarily it signifies the date of one's birth, and therefore some understand it figuratively - he was as innocent and good as a child of a year old; so the Chaldee paraphrase: he was without fault, like the son of a year. But, if we admit a figurative sense, it may as well intimate that he was ignorant and imprudent, and as unfit for business as a child of a year old: and the subsequent particulars make this more accordant with his character than the former. But we take it rather, as our own translation has it, Saul reigned one year, and nothing happened that was considerable, it was a year of no action; but in his second year he did as follows: - 1. he chose a band of 3000 men, of whom he himself commanded 2000, and his son Jonathan 1000, Sa1 13:2. The rest of the people he dismissed to their tents. If he intended these only for the guard of his person and his honorary attendants, it was impolitic to have so many, if for a standing army, in apprehension of danger from the Philistines, it was no less impolitic to have so few; and perhaps the confidence he put in this select number, and his disbanding the rest of that brave army with which he had lately beaten the Ammonites (Sa1 11:8-11), was looked upon as an affront to the kingdom, excited general disgust, and was the reason he had so few at his call when he had occasion for them. The prince that relies on a particular party weakens his own interest in the whole community. 2. He ordered his son Jonathan to surprise and destroy the garrison of the Philistines that lay near him in Geba, Sa1 13:3. I wish there were no ground for supposing that this was a violation or infraction of some articles with the Philistines, and that it was done treacherously and perfidiously. The reason why I suspect it is because it is said that, for doing it, Israel was had in abomination, or, as the word is, did stink with the Philistines (Sa1 13:4), as men void of common honesty and whose word could not be relied on. If it was so, we will lay the blame, not on Jonathan who did it, but on Saul, his prince and father, who ordered him to do it, and perhaps kept him in ignorance of the truth of the matter. Nothing makes the name of Israel odious to those that are without so much as the fraud and dishonesty of those that are called by that worthy name. If professors of religion cheat and over-reach, break their word and betray their trust, religion suffers by it, and is had in abomination with the Philistines. Whom may one trust if not an Israelite, one that, it is expected, should be without guile? 3. When he had thus exasperated the Philistines, then he began to raise forces, which, if he had acted wisely, he would have done before. When the Philistines had a vast army ready to pour in upon him, to avenge the wrong he had done them, then was he blowing the trumpet through the land, among a careless, if not a disaffected people, saying, Let the Hebrews hear (Sa1 13:3), and so as many as thought fit came to Saul to Gilgal, Sa1 13:4. But now the generality, we may suppose, drew back (either in dislike of Saul's politics or in dread of the Philistines' power), who, if he had summoned them sooner, would have been as ready at his beck as they were when he marched against the Ammonites. We often find that after-wit would have done much better before and have prevented much inconvenience.
II. Never did the Philistines appear in such a formidable body as they did now, upon this provocation which Saul gave them. We may suppose they had great assistance from their allies, for (Sa1 13:5), besides 6000 horse, which in those times, when horses were not so much used in war as they are now, was a great body, they had an incredible number of chariots, 30,000 in all: most of them, we may suppose, were carriages for the bag and baggage of so vast an army, not chariots of war. But their foot was innumerable as the sand of the sea-shore, so jealous were they for the honour of their nation and so much enraged at the baseness of the Israelites in destroying their garrison. If Saul had asked counsel of God before he had given the Philistines this provocation, he and his people might the better have borne this threatening trouble which they had now brought on themselves by their own folly.
III. Never were the people of Israel so faint-hearted, so sneaking, so very cowardly, as they were now. Some considerable numbers, it may be, came to Saul to Gilgal; but, hearing of the Philistines' numbers and preparations, their spirits sunk within them, some think because they did not find Samuel there with Saul. Those that, awhile ago, were weary of him, and wished for a king, now had small joy of their king unless they could see him under Samuel's direction. Sooner or later, men will be made to see that God and his prophets are their best friends. Now that they saw the Philistines making war upon them, and Samuel not coming in to help them, they knew not what to do; men's hearts failed them for fear. And. 1. Some absconded. Rather than run upon death among the Philistines, they buried themselves alive in caves and thickets, Sa1 13:6. See what work sin makes; it exposes men to perils, and then robs them of their courage and dispirits them. A single person, by faith, can say, I will not be afraid of 10,000 (Psa 3:6); but here thousands of degenerate Israelites tremble at the approach of a great crowd of Philistines. Guilt makes men cowards. 2. Others fled (Sa1 13:7): They went over Jordan to the land of Gilead, as far as they could from the danger, and to a place where they had lately been victorious over the Ammonites. Where they had triumphed they hoped to be sheltered. 3. Those that staid with Saul followed him trembling, expecting no other than to be cut off, and having their hands and hearts very much weakened by the desertion of so many of their troops. And perhaps Saul himself, though he had so much honour as to stand his ground, yet had no courage to spare wherewith to inspire his trembling soldiers.

Jonathan smote - He appears to have taken this garrison by surprise, for his men had no arms for a regular battle, or taking the place by storm. This is the first place in which this brave and excellent man appears; a man who bears one of the most amiable characters in the Bible.
Let the Hebrews hear - Probably this means the people who dwelt beyond Jordan, who might very naturally be termed here העברים haibrim, from עבר abar, he passed over; those who are beyond the river Jordan: as Abraham was called עברי Ibri because he dwelt beyond the river Euphrates.

And Jonathan smote the garrison of the Philistines that was in Geba,.... Not the same with Gibeah of Benjamin, as Jarchi; for it can hardly be thought that Jonathan should place himself with his thousand men where the Philistines had a garrison; or that if this was the same with that in the preceding verse, that it should be called by another name in this; but Gibeah and Geba were two places, as Kimchi observes, both indeed in the tribe of Benjamin, and it is very probable not far from one another; see Jos 18:24. This seems to be the same with the hill of God, where was a garrison of the Philistines, Sa1 10:5, who after their defeat by Samuel contented themselves with some strong holds and garrisons in some parts of the land to keep Israel in awe; the Targum understands this of a single person, a governor of the Philistines in this place, whom Jonathan slew, and so Jarchi; and according to R. Isaiah he was one that was appointed to gather the tax for them:

and the Philistines heard of it, which alarmed them, and made them prepare for war:

and Saul blew the trumpet throughout all the land; not he in person, for he was at Gilgal, as the next verse shows; but he ordered it to be blown, being aware of the preparations the Philistines were making to attack him:

saying, let the Hebrews hear; both what his son had done, and what the Philistines were doing.

HE CALLS THE HEBREWS TO GILGAL AGAINST THE PHILISTINES. (Sa1 13:3-4)

And Jonathan--that is, "God-given."

smote the garrison of the Philistines . . . in Geba--Geba and Gibeah were towns in Benjamin, very close to each other (Jos 18:24, Jos 18:28). The word rendered "garrison" is different from that of Sa1 13:23; Sa1 14:1, and signifies, literally, something erected; probably a pillar or flagstaff, indicative of Philistine ascendency. That the secret demolition of this standard, so obnoxious to a young and noble-hearted patriot, was the feat of Jonathan referred to, is evident from the words, "the Philistines heard of it," which is not the way we should expect an attack on a fortress to be noticed.

Saul blew the trumpet throughout all the land--This, a well-known sound, was the usual Hebrew war-summons; the first blast was answered by the beacon fire in the neighboring places. A second blast was blown--then answered by a fire in a more distant locality, whence the proclamation was speedily diffused over the whole country. As the Philistines resented what Jonathan had done as an overt attempt to throw off their yoke, a levy, en masse, of the people was immediately ordered, the rendezvous to be the old camping-ground at Gilgal.