1 Kings 12:26 - Joseph Benson’s Commentary on the Old and New Testaments

Jeroboam said in his heart Reasoned within himself. The sacred historian shows, by this phrase, the fountain of his error, that he did not consult God, who had given him the kingdom, as in all reason, and justice, and gratitude, he ought to have done; nor believed in and relied on God's promises, 1 Kings 11:38, but on his own carnal policy. God had told him he would build him a sure house, if he would walk in his ways and keep his statutes, yet he could not depend on this, but, agreeably to the propensity of his fallen nature, studied to establish his throne by his own wisdom, and so brought evil upon himself, and introduced an idolatry into his kingdom which in the end proved its ruin.