1 Chronicles 23:24

"Now the Levites were numbered from the age of thirty years and upward: and their number by their polls, man by man, was thirty and eight thousand."

"And the tabernacle was taken down; and the sons of Gershon and the sons of Merari set forward, bearing the tabernacle."

"And the Kohathites set forward, bearing the sanctuary: and the other did set up the tabernacle against they came."

"From thirty years old and upward even until fifty years old, all that enter into the host, to do the work in the tabernacle of the congregation."

"Now in the second year of their coming unto the house of God at Jerusalem, in the second month, began Zerubbabel the son of Shealtiel, and Jeshua the son of Jozadak, and the remnant of their brethren the priests and the Levites, and all they that were come out of the captivity unto Jerusalem; and appointed the Levites, from twenty years old and upward, to set forward the work of the house of the LORD."

"This is it that belongeth unto the Levites: from twenty and five years old and upward they shall go in to wait upon the service of the tabernacle of the congregation: to...: Heb. to war the warfare of, etc"

"Thou shalt even take five shekels apiece by the poll, after the shekel of the sanctuary shalt thou take them: (the shekel is twenty gerahs:)"

"For by the last words of David the Levites were numbered from twenty years old and above:"

"And they assembled all the congregation together on the first day of the second month, and they declared their pedigrees after their families, by the house of their fathers, according to the number of the names, from twenty years old and upward, by their polls."