We are now to take a view of the miserable state of Israel, while the kingdom of Judah was happy under Asa's good government. It was threatened that they should be as a reed shaken in the water (Kg1 14:15), and so they were, when, during the single reign of Asa, the government of their kingdom was in six or seven different hands, as we find in this and the following chapter. Jeroboam was upon the throne in the beginning of his reign and Ahab at the end of it, and between them were Nadab, Baasha, Elah, Zimri, Tibni, and Omri, undermining and destroying one another. This they got by deserting the house both of God and of David. Here we have, 1. The ruin and extirpation of the family of Jeroboam, according to the word of the Lord by Ahijah. His son Nadab succeeded him. If the death of his brother Abijah had had a due influence upon him to make him religious, and the honour done him at his death had engaged him to follow his good example, his reign might have been long and glorious; but he walked in the way of his father (Kg1 15:26), kept up the worship of his calves, and forbade his subjects to go up to Jerusalem to worship, sinned and made Israel to sin, and therefore God brought ruin upon him quickly, in the second year of his reign. He was besieging Gibbethon, a city which the Philistines had taken from the Danites, and was endeavouring to re-take it; and there, in the midst of his army, did Baasha, with others, conspire against him and kill him, (Kg1 15:27), and so little interest had he in the affections of his people that his army did not only not avenge his death, but chose his murderer for his successor. Whether Baasha did it upon a personal pique against Nadab, or to be avenged on the house of Jeroboam for some affront received from them, or whether under pretence of freeing his country from the tyranny of a bad prince, or whether merely from a principle of ambition, to make way for himself to the throne, does not appear; but he slew him and reigned in his stead, Kg1 15:28. And the first thing he did when he came to the crown was to cut off all the house of Jeroboam, that he might the better secure himself and his own usurped government. He thought it not enough to imprison or banish them, but he destroyed them, left not only no males (as was foretold, Kg1 14:10), but none that breathed. Herein he was barbarous, but God was righteous. Jeroboam's sin was punished (Kg1 15:30); for those that provoke God do it to their own confusion; see Jer 7:19. Ahijah's prophecy was accomplished (Kg1 15:29); for no word of God shall fall to the ground. Divine threatenings are not bugbears. 2. The elevation of Baasha. He shall be tried awhile, as Jeroboam was. Twenty-four years he reigned (Kg1 15:33), but showed that it was not from any dislike to Jeroboam's sin that he destroyed his family, but from malice and ambition; for, when he had rooted out the sinner, he himself clave to the sin, and walked in the way of Jeroboam (Kg1 15:34), though he had seen the end of that way; so strangely was his heart hardened with the deceitfulness of sin.

Nadab - began to reign over Israel - He began his reign in the second year of the reign of Asa, and reigned two years.

And there was war between Asa and Baasha king of Israel all their days. For being a wicked man, and an idolater, Asa had no respect for him, though he had slain the family of Jeroboam; nor had Baasha any regard to Judah, nor to the worship of God at Jerusalem, so that there was no good understanding between them, but frequent acts of hostility, see Kg1 15:16.
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1 Kings 15:33

kg1 15:33
kg1 15:33
kg1 15:33In the third year of Asa king of Judah began Baasha the son of Ahijah to reign over all Israel in Tirzah,.... Which is repeated, partly to observe that the whole kingdom submitted to him, though an usurper and murderer, and the place where he kept his court, as also the time of his reign, as follows:

twenty four years; which were as long as both Jeroboam and his son reigned.

NADAB'S WICKED REIGN. (Kg1 15:25-34)

Nadab the son of Jeroboam began to reign--No record is given of him, except his close adherence to the bad policy of his father.