Geba - Better, as in marginal reference "Gibeon." Gazer should be "Gezer" (Joshua 10:33, etc.); it lay between the nether Bethhoron and the sea; on the direct route therefore which the Philistines, fleeing from Gibeon, would take. The exact site has now been identified (1-Kings 9:16).

And David did so - He punctually obeyed the directions of the Lord, and then every thing succeeded to his wish.
How is it that such supernatural directions and assistances are not communicated now? Because they are not asked for; and they are not asked for because they are not expected; and they are not expected because men have not faith; and they have not faith because they are under a refined spirit of atheism, and have no spiritual intercourse with their Maker. Who believes that God sees all things and is everywhere? Who supposes that he concerns himself with the affairs of his creatures? Who acknowledges him in all his ways? Who puts not his own wisdom, prudence, and strength, in the place of God Almighty? Reader, hast thou faith in God? Then exercise it, cultivate it, and thou mayest remove mountains.
It is worthy of remark that David was, by the appointment of God, to feed the people. As he had formerly the care of a flock of sheep, which he was to watch over, defend, lead in and out, and for which he was to find pasture; now he is to watch over, defend, lead in and out, feed, and protect, the Israelites. He is to be the shepherd of the people, not the tyrant or oppressor.
In ancient times, among the Greeks, kings were denominated ποιμενες λαου, shepherds of the people; and all good kings were really such: but, in process of time, this pleasing title was changed for βασιλευς and τυραννος, sovereign and tyrant; in neither of which names does any thing of the original title exist. And such are the different political constitutions of the kingdoms of the earth, that it is impossible that in any of them, the British excepted, the king can be the shepherd and father of his people. All the other regal constitutions under the sun permit the sovereign to be despotic, and consequently oppressive and tyrannical if he please. The British alone gives no power of this kind to the prince; by the constitution he is a patriotic king, and by the influence of those maxims of state which are continually presented to his view, and according to which all acts of government are formed, he becomes habitually the father of his people, and in this light alone do the British people behold the British king.
David, by his own authority, without any form of law, could slay the Amalekite who said he had killed Saul; and could cut off the heads of Rechab and Baanah, who murdered Ish-bosheth; but, in the government of Britain, the culprit is to be heard in his vindication, witnesses are to be examined, the facts viewed by an upright judge in the light of the law; and then the alleged criminality is left to the decision of twelve honest men, the equals of the accused, who are bound by a solemn oath to decide according to the evidence brought before them. The Israelitish constitution was radically good, but the British constitution is much better. In the former, while the king ruled according to the spirit of the constitution, he could do no wrong, because he was only the vicegerent of the Almighty; in the latter, the king can do no wrong, because he is bound both by the spirit and letter of the law, to do nothing but what is according to the rules of eternal justice and equity laid down in that law; nothing is left to mere regal power or authority, and nothing trusted to human fickleness or caprice. In all his acts he is directed by his nobles and commons; who, being the representatives of all classes of the people, are always supposed to speak their mind. Well may it be said, Blessed are the people who are in such a case!

And David did so, as the LORD had commanded him; and smote the Philistines from Geba until thou come to (h) Gazer.
(h) Which was in the tribe of Benjamin, but the Philistines possessed it.

And David did so as the Lord commanded him,.... In all things he was obedient to the command of God; Saul was not: he got behind the army of the Philistines, as he was directed; and when he heard the sound in the mulberry trees, he arose and fell upon his enemies:
and smote the Philistines from Geba until thou come to Gazer; or from Gibeon, as in 1-Chronicles 14:16; a city in the tribe of Benjamin, near to which this battle was fought, and where the pursuit began, which was carried as far as Gazer, a city that lay on the borders of the Philistines, as Josephus says (b); and so far they were pursued, and were smitten as they fled; and, according to Bunting (c), it was a space of eighteen miles.
(b) Antiqu. l. 7. c. 4. sect. 1. (c) Travels, &c. p. 138.

David did this, and smote the Philistines from Geba to the neighbourhood of Gezer. In the Chronicles we find "from Gibeon" instead of from Geba. The former is unquestionably the true reading, and Geba an error of the pen: for Geba, the present Jeba, was to the north of Jerusalem, and on the east of Ramah (see at Joshua 18:24); so that it is quite unsuitable here. But that is not the case with Gibeon, the present el Jib, on the north-west of Jerusalem (see at Joshua 9:3); for this was on the way to Gezer, which was four Roman miles to the north of Amws, and is probably to be sought for on the site of the present el Kubab (see at Joshua 10:33).
(Note: There is no force in the objection brought by Bertheau against this view, viz., that "it is a priori improbable that the Philistines who were fighting against David and his forces, whose base of operations was Jerusalem, should have taken possession of the whole line from Gibeon to Gezer," as the improbability is by no means apparent, and has not been pointed out by Bertheau, whilst the assumption that Jerusalem was David's base of operations has no foundation whatever. Moreover, Bertheau's opinion, that Geba was the same as Gibeah in the tribe of Judah (Joshua 15:57), is decidedly erroneous: for this Gibeah is not to be identified with the present village of Jeba on the south side of the Wady Musurr, half-way between Shocoh and Jerusalem, but was situated towards the desert of Judah (see at Joshua 15:57); and besides, it is impossible to see how the Philistines, who had invaded the plain of Rephaim, could have been beaten from this Gibeah as far as to Gezer.)