Reading today in 2 Chronicles 29 through 31.

Then they killed the passover on the fourteenth day of the second month: and the priests and the Levites were ashamed, and sanctified themselves, and brought in the burnt offerings into the house of the LORD.  And they stood in their place after their manner, according to the law of Moses the man of God: the priests sprinkled the blood, which they received of the hand of the Levites.  For there were many in the congregation that were not sanctified: therefore the Levites had the charge of the killing of the passovers for every one that was not clean, to sanctify them unto the LORD.  For a multitude of the people, even many of Ephraim, and Manasseh, Issachar, and Zebulun, had not cleansed themselves, yet did they eat the passover otherwise than it was written. But Hezekiah prayed for them, saying, “The good LORD pardon every one that prepareth his heart to seek God, the LORD God of his fathers, though he be not cleansed according to the purification of the sanctuary.”
And the LORD hearkened to Hezekiah, and healed the people.
2 Chronicles 30:15-20