1 Kings 12:31-32

31And he made a house of high places, and made priests from all classes of the people, who were not of the sons of Levi.

32And Jeroboam ordained a feast in the eighth month, on the fifteenth day of the month, like the feast that was in Judah, and he offered upon the altar. So did he in Bethel, sacrificing to the calves that he had made; and he placed in Bethel the priests of the high places that he had made.