Biblical Commentary on the Old Testament, by Carl Friedrich Keil and Franz Delitzsh, [1857-78], at sacred-texts.com
2 Chronicles 12:1
Rehoboam's defection from the Lord, and his humiliation by the Egyptian king Shishak. - Ch2 12:1. The infinitive כּהכין, "at the time of the establishing," with an indefinite subject, may be expressed in English by the passive: when Rehoboam's royal power was established. The words refer back to Ch2 11:17. כּחזקתו, "when he had become strong" (חזקה is a nomen verbale: the becoming strong; cf. Ch2 26:16; Ch2 11:2), he forsook the Lord, and all Israel with him. The inhabitants of the kingdom of Judah are here called Israel, to hint at the contrast between the actual conduct of the people in their defection from the Lord, and the destiny of Israel, the people of God. The forsaking of the law of Jahve is in substance the fall into idolatry, as we find it stated more definitely in Kg1 14:22.
2 Chronicles 12:2
In punishment of this defection (בי מעלוּ כּי, because they had acted faithlessly to Jahve), Shishak, the king of Egypt, marched with a great host against Jerusalem. This hostile invasion is also briefly narrated in Kg1 14:25-28. Shishak (Sisak) is, as we have remarked on 1 Kings 14, Sesonchis or Sechonchosis, the first king of the 22nd dynasty, who has celebrated his victory in a relief at Karnak. In this sculpture the names of the cities captured are recorded on shields, and a considerable number have been deciphered with some certainty, and by them our account is completely confirmed. According to Ch2 12:3, Shishak's host consisted of 1200 chariots, 60,000 horsemen-numbers which, of course, are founded only upon a rough estimate-and an innumerable multitude of footmen, among whom were לוּבים, Libyans, probably the Libyaegyptii of the ancients (see on Gen 10:13); סכּיּים, according to the lxx and Vulg. Troglodytes, probably the Ethiopian Troglodytes, who dwelt in the mountains on the west coast of the Arabian Gulf; and Cushites, i.e., Ethiopians. The Libyans and Cushites are mentioned in Nah 3:9 also as auxiliaries of the Egyptians.
2 Chronicles 12:4
After the capture of the fenced cities of Judah, he marched against Jerusalem. - Ch2 12:5. Then the prophet Shemaiah announced to the king and the princes, who had retired to Jerusalem before Shishak, that the Lord had given them into the power of Shishak because they had forsaken Him. בּיד עזב, forsaken and given over into the hand of Shishak. When the king and the priests immediately humbled themselves before God, acknowledging the righteousness of the Lord, the prophet announced to them further that the Lord would not destroy them since they had humbled themselves, but would give them deliverance in a little space. כּמעט, according to a little, i.e., in a short time. פּליטה is accusative after ונתתּי. My anger shall not pour itself out upon Jerusalem. The pouring out of anger is the designation of an exterminating judgment; cf. Ch2 34:25.
2 Chronicles 12:8
But (כּי after a negative clause) they shall be his servants, sc. for a short time (see Ch2 12:7), "that they may know my service, and the service of the kingdoms of the countries" (cf. Ch1 29:30); i.e., that they may learn to know by experience the difference between the rule of God and that of the heathen kings, and that God's rule was not so oppressive as that of the rulers of the world.
2 Chronicles 12:9
With Ch2 12:9 the account of the war is taken up again and continued by the repetition of the words, "Then marched Shishak ... against Jerusalem" (Ch2 12:4). Shishak plundered the treasures of the temple and the palace; he had consequently captured Jerusalem. The golden shields also which had been placed in the house of the forest of Lebanon, i.e., the palace built by Solomon in Jerusalem, which Solomon had caused to be made (cf. Ch2 9:16), Shishak took away, and in their place Rehoboam caused brazen shields to be prepared; see on Kg1 14:26-28. - In Ch2 12:12 the author of the Chronicle concludes the account of this event with the didactic remark, "Because he (Rehoboam) humbled himself, the anger of Jahve was turned away from him." להשׁחית ולא, and it was not to extermination utterly (לכלה, properly to destruction, i.e., completely; cf. Eze 13:13). And also in Judah were good things. This is the other motive which caused the Lord to turn away His wrath. Good things are proofs of piety and fear of God, cf. Ch2 19:3.
2 Chronicles 12:13
The length of Rehoboam's reign, his mother, and the judgment about him. Cf. Kg1 14:21 and Kg1 14:22. ויּתחזּק here, as in Ch2 13:21, can, in its connection with what precedes, be only understood to mean that Rehoboam, after his humiliation at the hands of Shishak, by which his kingdom was utterly weakened and almost destroyed, again gained strength and power. Cf. also Ch2 1:1, where יתחזּק is used of Solomon in the beginning of his reign, after he overcame Adonijah, the pretender to the crown, and his party. - As to the age of Rehoboam, etc., see on Kg1 14:21. הרע ויּעשׂ, Ch2 12:14, is defined by the addition, "for he prepared not his heart to seek the Lord." For the expression cf. Ch2 19:3; Ch2 30:19; Ezr 7:10.
2 Chronicles 12:15
Close of his reign. On the authorities, see the Introduction, and in reference to the other statements, the commentary on Kg1 14:29-31. מלחמות, wars, i.e., a state of hostility, was between Rehoboam and Jeroboam all days, can only be understood of the hostile attitude of the two rulers to each other, like מלחמה in Kings; for we have no narrative of wars between them after Rehoboam had abandoned, at the instance of the prophet, his proposed war with the Israelites at the commencement of his reign.