They slaughtered the Passover lamb on the fourteenth day of the second month. The priests and Levites were ashamed, and they consecrated themselves and brought burnt offerings to the Lord's temple. They stood at their prescribed posts, according to the law of Moses the man of God. The priests sprinkled the blood [received] from the hand of the Levites, for there were many in the assembly who had not consecrated themselves, and so the Levites were in charge of slaughtering the Passover [lambs] for every unclean person to consecrate [the lambs] to the Lord. read more.
For a large number of the people-many from Ephraim, Manasseh, Issachar, and Zebulun-were unclean, yet they had eaten the Passover contrary to what was written. But Hezekiah had interceded for them, saying, "May the good Lord provide atonement on behalf of whoever sets his whole heart on seeking God, the Lord God of his ancestors, even though not according to the purification [rules] of the sanctuary."

The Jewish Passover was near, and many went up to Jerusalem from the country to purify themselves before the Passover. Verse ConceptsPassoverPurifying OneselfNear The Time Generally