2 Chronicles 30:1-3, 13-20

Hezekiah sent to all Israel and Judah, and wrote letters also to Ephraim and Manasseh, that they should come to the house of the LORD at Jerusalem to keep the Passover to the LORD, the God of Israel. For the king and his princes and all the assembly in Jerusalem had taken counsel to keep the Passover in the second month— for they could not keep it at that time because the priests had not consecrated themselves in sufficient number, nor had the people assembled in Jerusalem

And many people came together in Jerusalem to keep the Feast of Unleavened Bread in the second month, a very great assembly. They set to work and removed the altars that were in Jerusalem, and all the altars for burning incense they took away and threw into the brook Kidron. And they slaughtered the Passover lamb on the fourteenth day of the second month. And the priests and the Levites were ashamed, so that they consecrated themselves and brought burnt offerings into the house of the LORD. They took their accustomed posts according to the Law of Moses the man of God. The priests threw the blood that they received from the hand of the Levites. For there were many in the assembly who had not consecrated themselves. Therefore the Levites had to slaughter the Passover lamb for everyone who was not clean, to consecrate it to the LORD. For a majority of the people, many of them from Ephraim, Manasseh, Issachar, and Zebulun, had not cleansed themselves, yet they ate the Passover otherwise than as prescribed. For Hezekiah had prayed for them, saying, “May the good LORD pardon everyone who sets his heart to seek God, the LORD, the God of his fathers, even though not according to the sanctuary’s rules of cleanness.” And the LORD heard Hezekiah and healed the people.