Numbers 8:23-26 - Retirement Of The Levites
23 And Yahweh spake unto Moses saying; 24 This is what concerneth the Levites, - from twenty-five years old and upwards, shall they enter to take rank in the host, for doing the laborious work of the tent of meeting; 25 but from the age of fifty years, shall they retire from taking rank in the labour, and shall do laborious work no more; 26 yet shall they wait upon their brethren in the tent of meeting, by keeping charge, but laborious work, shall they not perform, - thus, shalt thou do unto the Levites, as touching their charges.