Notes on the Bible, by Albert Barnes, [1834], at sacred-texts.com
Enquired of the Lord - Through Abiathar, the high priest. The death of Saul and Jonathan had entirely changed David's position, and therefore he needed divine guidance how to act under the new circumstances in which he was placed. Compare the marginal references.
Hebron was well suited for the temporary capital of David's kingdom, being situated in a strong position in the mountains of Judah, amidst David's friends, and withal having especially sacred associations (see the marginal references note). It appears to have also been the center of a district Sa2 2:3.
David had already been anointed by Samuel Sa1 16:13. His first anointing indicated God's secret purpose, his second the accomplishment of that purpose. (Compare the case of Saul, Sa1 10:1; Sa1 11:14.) David was anointed again king over Israel Sa2 5:3. The interval between the anointing of the Lord Jesus as the Christ of God, and His taking to Himself His kingdom and glory, seems to be thus typified.
Mahanaim - See Gen 32:2. From Sa2 2:12 it would seem to have been Ish-bosheth's capital.
The Ashurites - If the tribe of Asher, the verse indicates the order in which Abner recovered the different districts from the Philistines, and added them to the dominions of Ish-bosheth, beginning with Gilead, and then gradually adding, on the west of Jordan, first the territory of Asher as far as Carmel and the whole plain of Esdraelon, and then the country of Ephraim and Benjamin, being in fact all Israel, as distinguished from Judah; and this reconquest may have occupied five years. Ish-bosheth's reign over Israel may not have been reckoned to begin until the conquest was complete.
Forty ... two - The numerals are somewhat strange. First, as regards the 40 years. Even assuming that Ish-bosheth's reign did not commence until five and a half years after Saul's death, which must have been the case if the two years in the text gives the true length of his reign, it is startling to hear of Saul's younger son being 35 years old at his father's death, born consequently some three years before his father's accession, and five years older than David, the bosom friend of his older brother Jonathan. The age, too, of Jonathan's child, Mephibosheth, who was five years old at his father's death, would lead one to expect rather a less age for his uncle. Next, as regards the two years. Since David (compare Sa2 2:11; and marginal references) reigned seven years in Hebron over Judah only, it follows, if the two years in the text are correct, either that an interval of five years elapsed between Ish-bosheth's death and David's being anointed "king over all Israel," or that a like interval elapsed between Saul's death and the commencement of Ish-bosheth's reign. Of the two the latter is the more probable, and has the advantage of diminishing Ish-bosheth's age by between five and six years. But the narrative in 2 Sam. 3; Sa2 4:1-12 of the "long war," of the birth of David's six sons, and of Abner's conspiracy and death, seems to imply a longer time than two years, in which case both the numerals would have to be corrected.
This expedition to Gibeon may have been for the purpose of shifting his metropolis to his own tribe of Benjamin, and to his family place, "Gibeah of Saul," close to Gibeon, with the further purpose of attacking the kingdom of David. "To go out" Sa2 2:12-13 is a technical phrase for going out to war Sa1 18:30.
On the east of the hill (El-jib, the ancient Gibeon) is a copious spring, which issues in a cave excavated in the limestone rock, so as to form a large reservoir. In the trees further down are the remains of a pool or tank of considerable size (120 feet by 110 feet). This is doubtless "the pool of Gibeon."
Sat down - i. e. halted and encamped.
Play - (Compare Jdg 16:25; Sa1 18:7). Here, the word is applied to the serious game of war, to be played by twelve combatants on each side, with the two armies for spectators.
Compare Livy's history of the battle between the Horatii and Curiatii. This combat, like that, may have been proposed as a means of avoiding the effusion of blood of two nations united by consanguinity, and having a common powerful enemy in the Philistines.
Helkath-hazzurim - i. e. "the part, field, or plat Gen 23:19 of the sharp edges or blades." This seems, on the whole, the best explanation of this rather obscure name.
Neither side had the advantage in the combat of twelve a side; hence, the quarrel was fought out with great fierceness by the two armies, and the victory was won by David.
His armour - Rather, as in the margin; i. e. content thyself with the spoil of some inferior soldier for a trophy.
With the hinder end ... - i. e. the wooden end, which was more or less pointed to enable the owner to stick it in the ground Sa1 26:7.
The fifth rib - The word so rendered here (and in marginal references) means the abdomen, and is not etymologically connected with the Hebrew for five, as the translation "fifth rib" supposes, but with a verb meaning to be fat, or strong.
Ammah ... Giah - Local, and otherwise unknown names.
Joab's speech means either "unless thou hadst spoken (challenged us to fight, Sa2 2:14), the people would have returned from the pursuit of their brethren (many hours ago, even) this morning;" or, "If thou hadst not spoken (asked for peace, Sa2 2:26), surely the people would have returned, etc., in the morning, i. e. would not have ceased the pursuit until the morning." The latter interpretation is the more accordant with Joab's boastful character.
Through the plain - See Sa1 23:24. Bithron is unknown. From the expression all (the) Bithron, it seems likely that it is a tract of country, intersected by ravines lying on the east side of Jordan.
Joab, having stopped the pursuit, passed the night with his army on the field of battle; the next morning he numbered the missing, and buried the dead; they carried the body of Asahel to Bethlehem and buried him there, and then joined David at Hebron. Hebron would be about 14 miles from Bethlehem, or about five hours' march.