Numbers 8:23

"And Jehovah spake unto Moses, saying, This is that which belongeth unto the Levites: from twenty and five years old and upward they shall go in to wait upon the service in the work of the tent of meeting, and from the age of fifty years they shall cease waiting upon the work, and shall serve no more, but shall minister with their brethren in the tent of meeting, to keep the charge, and shall do no service. Thus shalt thou do unto the Levites touching their charges."

There are a number of important considerations in these verses. First, there is the "contradiction" in the giving of age twenty-five as the age when Levites began their service, whereas, previously the age of thirty years was specified. Different situations in view explain the difference: "The age varied for different kinds of service:

(1) for a soldier, it was age twenty,

(2) for a priest, it was age thirty, and

(3) for the Levites, it was age twenty-five."[17]

As for the age of thirty indicated for Levites in Numbers 4:3, this evidently referred particularly to those charged with moving the sacred furniture of the tabernacle. The work envisioned here is of a much wider nature. Another explanation, suggested by some, is that an apprenticeship of five years was also required, which would account for the variation. Whitelaw commented that:

"The directions in Numbers 4:3 (for an age of thirty years) concerned the transport of the tabernacle and its belongings; this was a permanent regulation designed for ordinary labors of the sanctuary at a time when the Levites would be scattered throughout their cities, and could only serve by courses. Even at the age of twenty-five, it was difficult to provide the required number in the latter days of King David."[18]

"To keep the charge ..." (Numbers 8:26; Numbers 1:53). This expression has the meaning of "stand guard over," or "standing guard."[19]