Ezra 3:8
In the second year after they had come to the temple of God in Jerusalem, in the second month, Zerubbabel the son of Shealtiel and Jeshua the son of Jozadak initiated the work, along with the rest of their associates, the priests and the Levites, and all those who were coming to Jerusalem from the exile. They appointed the Levites who were at least twenty years old to take charge of the work on the Lord's temple.
Numbers 4:3
from thirty years old and upward to fifty years old, all who enter the company to do the work in the tent of meeting.
1 Chronicles 23:4
David said, "Of these, 24,000 are to direct the work of the Lord's temple; 6,000 are to be officials and judges;
1 Chronicles 23:24-32
These were the descendants of Levi according to their families, that is, the leaders of families as counted and individually listed who carried out assigned tasks in the Lord's temple and were twenty years old and up.
Ezra 4:3
But Zerubbabel, Jeshua, and the rest of the leaders of Israel said to them, "You have no right to help us build the temple of our God. We will build it by ourselves for the Lord God of Israel, just as King Cyrus, the king of Persia, has commanded us."