Albert Barnes Commentary 1 Kings 16:7

"And moreover by the prophet Jehu the son of Hanani came the word of Jehovah against Baasha, and against his house, both because of all the evil that he did in the sight of Jehovah, to provoke him to anger with the work of his hands, in being like the house of Jeroboam, and because he smote him." — 1 Kings 16:7 (ASV)

The natural position of this verse would be after 1 Kings 16:4 and before 1 Kings 16:5. It may, however, be regarded as an afterthought added by the writer, somewhat irregularly. Its special purpose is to point out that the sentence on Baasha was intended to punish not only his calf-worship but emphatically his murder of Jeroboam and his family.

Although the destruction of Jeroboam’s house had been foretold, and Baasha may be rightly regarded as God’s instrument to punish Jeroboam’s sins, his guilt was just as great as if no prophecy had been uttered. This is because he received no command to execute God’s wrath on the offender and was motivated solely by ambition and self-interest. Even Jehu’s commission in 2 Kings 9:5–10 was not held to justify his murder of Jehoram and Jezebel altogether.