* cease waiting upon the service thereof.  Heb. return from the
   warfare of the service.
  4:23  2Ti 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
   disqualifying the Levites; but the time of their service is
   expressly settled.  Their work was far more laborious than
   that of the priests; it is therefore likely that the priests
   would not begin very early to officiate; and the wisdom and
   experience of age would increase, rather than diminish, their
   fitness for the sacred duties of their office.