Ezra 6:20-21

201For the priests and the Levites had purified themselves together; all of them were pure. Then 2they slaughtered the Passover lamb for all the exiles, both for their brothers the priests and for themselves.

21The sons of Israel who returned from exile and 3all those who had separated themselves from 4the impurity of the nations of the land to join them, to seek the Lord God of Israel, ate the Passover.