Then Jeroboam said to himself, "Now the kingdom may well revert to the house of David.
If this people continues to go up to offer sacrifices in the house of the Lord at Jerusalem, the heart of this people will turn again to their master, King Rehoboam of Judah; they will kill me and return to King Rehoboam of Judah."
So the king took counsel, and made two calves of gold. He said to the people, "You have gone up to Jerusalem long enough. Here are your gods, O Israel, who brought you up out of the land of Egypt."
References for 1 Kings 12:28
He set one in Bethel, and the other he put in Dan.
And this thing became a sin, for the people went to worship before the one at Bethel and before the other as far as Dan.
References for 1 Kings 12:30
He also made houses on high places, and appointed priests from among all the people, who were not Levites.
References for 1 Kings 12:31
Jeroboam appointed a festival on the fifteenth day of the eighth month like the festival that was in Judah, and he offered sacrifices on the altar; so he did 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.
He went up to the altar that he had made in Bethel on the fifteenth day in the eighth month, in the month that he alone had devised; he appointed a festival for the people of Israel, and he went up to the altar to offer incense.