Numbers 8:25
and from the age of fifty years they shall cease waiting upon the work, and shall serve no more,
Numbers 4:23
from thirty years old and upward until fifty years old shalt thou number them; all that enter in to wait upon the service, to do the work in the tent of meeting.
2 Timothy 4:7
I have fought the good fight, I have finished the course, I have kept the faith:
Treasury of Scripture Knowledge
Summary
                            And from the age of fifty years they shall cease waiting upon the service thereof, and shall serve no more:                        
                    General references
Bible References
General references
                                        Numbers 4:35                                        
                                                            
                        from thirty years old and upward even unto fifty years old, every one that entered upon the service, for work in the tent of meeting: