Numbers 9:10

“Command the sons of Israel that they send away from the camp every leper and everyone having a discharge and everyone who is unclean because of a dead person.

And the king and his princes and all the assembly in Jerusalem had taken counsel to celebrate the Passover in the second month,

For a multitude of the people, even many from Ephraim and Manasseh, Issachar, and Zebulun, had not cleansed themselves, yet they ate the Passover otherwise than what was written. For Hezekiah prayed for them, saying, “May Yahweh, who is good, atone

Now the Passover of the Jews was near, and many went up to Jerusalem from the region before the Passover to purify themselves.