2 Chronicles 35:16-19

16So on that day the entire service of Adonai was prepared to keep the Passover and to offer burnt offerings upon the altar of Adonai according to the command of King Josiah.

17The Bnei-Yisrael present celebrated the Passover at that time and observed the Feast of Matzot for seven days.

18Passover had not been celebrated like that in Israel since the days of Samuel the prophet, and none of the kings of Israel had ever celebrated such a Passover as Josiah did with the kohanim, the Levites, all Judah and Israel who were present and the inhabitants of Jerusalem.

19This Passover was celebrated in the eighteenth year of the reign of Josiah.