1 Kings 12:32 (KJV)

And this thing became a sin: for the people went to worship before the one, even unto Dan.

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.