Ezra 6:19-22

And the descendants of the captivity kept the Passover on the fourteenth day of the first month. For the priests and the Levites had purified themselves; all of them were ritually clean. And they slaughtered the Passover lambs for all the descendants of the captivity, for their brethren the priests, and for themselves. Then the children of Israel who had returned from the captivity ate together with all who had separated themselves from the filth of the nations of the land in order to seek the LORD God of Israel. And they kept the Feast of Unleavened Bread seven days with joy; for the LORD made them joyful, and turned the heart of the king of Assyria toward them, to strengthen their hands in the work of the house of God, the God of Israel.