A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown [1882] at sacred-texts.com
In his days the land was quiet ten years--This long interval of peace was the continued effect of the great battle of Zemaraim (compare Kg1 15:11-14).
Asa did that which was good and right--(compare Kg1 15:14). Still his character and life were not free from faults (Ch2 16:7, Ch2 16:10, Ch2 16:12).
brake down the images--of Baal (see on Ch2 34:4; Lev 26:30).
cut down the groves--rather, "Asherim."
he took away . . . the high places--that is, those devoted to idolatrous rites.
took away out of all the cities of Judah the high places and the images--All public objects and relics of idolatry in Jerusalem and other cities through his kingdom were destroyed; but those high places where God was worshipped under the figure of an ox, as at Beth-el, were allowed to remain (Kg1 15:14); so far the reformation was incomplete.
HAVING PEACE, HE STRENGTHENS HIS KINGDOM WITH FORTS AND ARMIES. (Ch2 14:6-8)
he built fenced cities in Judah--(See on Kg1 15:22).
while the land is yet before us--that is, while we have free and undisputed progress everywhere; no foe is near; but, as this happy time of peace may not last always and the kingdom is but small and weak, let us prepare suitable defenses in case of need. He had also an army of five hundred eighty thousand men. Judah furnished the heavily armed soldiers, and Benjamin the archers. This large number does not mean a body of professional soldiers, but all capable of bearing arms and liable to be called into service.
HE OVERCOMES ZERAH, AND SPOILS THE ETHIOPIANS. (Ch2 14:9-15)
there came out against them Zerah the Ethiopian--This could not have been from Ethiopia south of the cataracts of the Nile, for in the reign of Osorkon I, successor of Shishak, no foreign army would have been allowed a free passage through Egypt. Zerah must, therefore, have been chief of the Cushites, or Ethiopians of Arabia, as they were evidently a nomad horde who had a settlement of tents and cattle in the neighborhood of Gerar.
a thousand thousand, and three hundred chariots--"Twenty camels employed to carry couriers upon them might have procured that number of men to meet in a short time. As Zerah was the aggressor, he had time to choose when he would summon these men and attack the enemy. Every one of these Cushite shepherds, carrying with them their own provisions of flour and water, as is their invariable custom, might have fought with Asa without eating a loaf of Zerah's bread or drinking a pint of his water" [BRUCE, Travels].
Then Asa went out against him, and they set the battle in array . . . at Mareshah--one of the towns which Rehoboam fortified (Ch2 11:8), near a great southern pass in the low country of Judah (Jos 15:44). The engagement between the armies took place in a plain near the town, called "the valley of Zephathah," supposed to be the broad way coming down Beit Jibrin towards Tell Es-Safren [ROBINSON].
Asa cried unto the Lord his God--Strong in the confidence that the power of God was able to give the victory equally with few as with many, the pious king marched with a comparatively small force to encounter the formidable host of marauders at his southern frontier. Committing his cause to God, he engaged in the conflict--completely routed the enemy, and succeeded in obtaining, as the reward of his victory, a rich booty in treasure and cattle from the tents of this pastoral horde.