2 Kings 23:20-24

Josiah slaughtered all the priests of those high places on the altars and burned human bones on them. Then he went back to Jerusalem.

The king gave this order to all the people: “Celebrate the Passover to the Lord your God, as it is written in this Book of the Covenant.”

Neither in the days of the judges who led Israel nor in the days of the kings of Israel and the kings of Judah had any such Passover been observed.

But in the eighteenth year of King Josiah, this Passover was celebrated to the Lord in Jerusalem.

Furthermore, Josiah got rid of the mediums and spiritists, the household gods, the idols and all the other detestable things seen in Judah and Jerusalem. This he did to fulfill the requirements of the law written in the book that Hilkiah the priest had discovered in the temple of the Lord.