1 Kings 12:31-32

31Jeroboam built shrines on high places and appointed priests from all sorts of people, even though they were not Levites.

32He instituted a festival on the fifteenth day of the eighth month, like the festival held in Judah, and offered sacrifices on the altar. This he did in Bethel, sacrificing to the calves he had made. And at Bethel he also installed priests at the high places he had made.