Ezra 6:20-21

20The priests and the Levites had purified themselves, every last one, and they all were ceremonially pure. They sacrificed the Passover lamb for all the exiles, for their colleagues the priests, and for themselves.

21The Israelites who were returning from the exile ate it, along with all those who had joined them in separating themselves from the uncleanness of the nations of the land to seek the Lord God of Israel.