Ezra 3:8 NIV

8 In the second month of the second year after their arrival at the house of God in Jerusalem, Zerubbabel son of Shealtiel, Joshua son of Jozadak and the rest of the people (the priests and the Levites and all who had returned from the captivity to Jerusalem) began the work. They appointed Levites twenty years old and older to supervise the building of the house of the LORD.

References for Ezra 3:8