2 Chronicles 30:13-17

So a huge crowd assembled at Jerusalem in midspring to celebrate the Festival of Unleavened Bread. They set to work and removed the pagan altars from Jerusalem. They took away all the incense altars and threw them into the Kidron Valley. On the fourteenth day of the second month, one month later than usual, the people slaughtered the Passover lamb. This shamed the priests and Levites, so they purified themselves and brought burnt offerings to the Temple of the LORD. Then they took their places at the Temple as prescribed in the Law of Moses, the man of God. The Levites brought the sacrificial blood to the priests, who then sprinkled it on the altar. Since many of the people had not purified themselves, the Levites had to slaughter their Passover lamb for them, to set them apart for the LORD.