1 Kings 12:33
“So he offered upon the altar which he had made in Beth–el the fifteenth day of the eighth month, even in the month which he had devised of his own heart; and ordained a feast unto the children of Israel: and he offered upon the altar, and burnt incense.”
And he made an house of high places, and made priests of the lowest of the people, which were not of the sons of Levi.
And Jeroboam ordained a feast in the eighth month, on the fifteenth day of the month, like unto the feast that is in Judah, and he offered upon the altar. So did he in Beth–el, sacrificing unto the calves that he had made: and he placed in Beth–el the priests of the high places which he had made.
So he offered upon the altar which he had made in Beth–el the fifteenth day of the eighth month, even in the month which he had devised of his own heart; and ordained a feast unto the children of Israel: and he offered upon the altar, and burnt incense.
Counter-Arguments
The strongest case that this verse does not belong in this theme.

Cross-References
“And he went forth and warred against the Philistines, and brake down the wall of Gath, and the wall of Jabneh, and the wall of Ashdod, and built cities about Ashdod, and among the Philistines.”
“Thus were they defiled with their own works, and went a whoring with their own inventions.”
“And it shall be unto you for a fringe, that ye may look upon it, and remember all the commandments of the Lord, and do them; and that ye seek not after your own heart and your own eyes, after which ye use to go a whoring:”
“And honour not his father or his mother, he shall be free. Thus have ye made the commandment of God of none effect by your tradition.”
“Wherefore the Lord said, Forasmuch as this people draw near me with their mouth, and with their lips do honour me, but have removed their heart far from me, and their fear toward me is taught by the precept of men:”