Ezra 6:19-22

On the fourteenth day of the first month, the returned exiles kept the Passover. For the priests and the Levites had purified themselves together; all of them were clean. So they slaughtered the Passover lamb for all the returned exiles, for their fellow priests, and for themselves. It was eaten by the people of Israel who had returned from exile, and also by every one who had joined them and separated himself from the uncleanness of the peoples of the land to worship the LORD, the God of Israel. And they kept the Feast of Unleavened Bread seven days with joy, for the LORD had made them joyful and had turned the heart of the king of Assyria to them, so that he aided them in the work of the house of God, the God of Israel.