Numbers 8:25

“And from the age of fifty years they shall cease waiting upon the service [thereof], etc.] The heavy service of it: and shall serve no more; by bearing and carrying the vessels of the sanctuary upon their shoulders, as Jarchi interprets it; this, according to the Jewish writers, was only in force while the tabernacle was in the wilderness, and was moved from place to place: but when it had a fixed habitation, and that laborious service of bearing and carrying the vessels of it ceased, years made no difference in the Levites, or disqualified them for service; for it is said f90, that the Levites were not bound by this law, but in the time of the tabernacle; but when it was at Shiloh, and at…”

“from the age of fifty years they shall cease waiting upon the service thereof, &c.--that is, on the laborious and exhausting parts of their work.”

“cease waiting upon the service thereof: Heb. return from the warfare of the service, Num 4:23; Ti2 4:7; The Levites, above fifty years of age, might superintend and assist their junior brethren in the ordinary offices, and give them and the people counsel and instruction; but they were exempted from carrying the tabernacle and from other laborious services. It is remarkable, that no law was made concerning the age at which the priests should begin to officiate, and though various blemishes disqualified them for the service of the sanctuary, yet they continued their ministrations till death, if capable. On the other hand, nothing is said concerning any bodily defects or blemishes…”