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 burnt offerings into the house of Yahweh. They stood in their place after their order, 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 assembly who had not sanctified themselves: therefore the Levites were in charge of killing the Passovers for everyone who was not clean, to sanctify them to Yahweh. read more.
For a multitude of the people, even many of Ephraim and Manasseh, Issachar and Zebulun, had not cleansed themselves, yet they ate the Passover otherwise than it is written. For Hezekiah had prayed for them, saying, "May the good Yahweh pardon everyone who sets his heart to seek God, Yahweh, the God of his fathers, even if they aren't clean according to the purification of the sanctuary."

Now the Passover of the Jews was at hand. Many went up from the country to Jerusalem before the Passover, to purify themselves. Verse ConceptsPassoverPurifying OneselfNear The Time Generally