The last verse of 1 Kings 12:1–33 contains the further disobedience of Jeroboam. He designs a feast that is similar to the feast of booths, but ordains that it should be in the eighth month rather than in the seventh month as the law of Moses required. The text makes this clear by saying that the month was something that he devised in his own heart.
The horrendous nature of Jeroboam’s actions at this point is incalculable. He usurps not only Moses’ place but God’s place as well. While he thought he was taking action that would establish his rule and his dynasty, its result was to doom him and his dynasty. God had promised him a sure house at the price of faithful obedience. Jeroboam chose to repudiate that promise because he had no faith in Almighty God.
32 And Jeroboam appointed a feast on the fifteenth day of the eighth month like the feast that was in Judah, and he offered sacrifices on the altar. So he did in Bethel, sacrificing to the calves that he made. And he placed in Bethel the priests of the high places that he had made.