From thirty years old and upward even until fifty years old, all that enter into the host, to do the work in the tabernacle of the congregation.

From thirty years old and upward, to fifty years old, of all that go in to stand and to minister in the tabernacle of the covenant.

from a son of thirty years and upward, even till a son of fifty years, every one going in to the host, to do work in the tent of meeting.

All those from thirty to fifty years old who are able to do the work of the Tent of meeting.

from thirty years and above, even to the fiftieth year, of all who enter so as to stand and minister in the tabernacle of the covenant.

Ab eo qui natus est triginta annos et supra, usque ad eum qui natus est quinquaginta annos, quotquot ingrediuntur congregationem, ut faciant opus in tabernaculo conventionis.

From thirty years old - In Numbers 8:24, the Levites are ordered to enter on the service of the tabernacle at the age of twenty-five years; and in 1-Chronicles 23:24, they were ordered to commence that work at twenty years of age. How can these different times be reconciled?
1. At the time of which Moses speaks here, the Levitical service was exceedingly severe, and consequently required men full grown, strong, and stout, to perform it; the age therefore of thirty years was appointed as the period for commencing this service, the weightier part of which is probably here intended.
2. In Numbers 8:24, Moses seems to speak of the service in a general way; the severe, which was to be performed by the full-grown Levites, and the less laborious work which younger men might assist in: hence the age of twenty-five is fixed.
3. In David's time and afterwards, in the fixed tabernacle and temple, the laboriousness of the service no longer existed, and hence twenty years was the age fixed on for all Levites to enter into the work of the sanctuary. The rabbins say that the Levites began to learn to do the service at twenty-five, and that having been instructed five years, they began the public service at thirty, and thus they reconcile the two periods referred to above. We may well suppose that the sons of the prophets continued a considerable time under instructions before they were called fully to exercise themselves in the prophetic office.
Until fifty years old - This was allowing twenty years for public severe service; a very considerate and merciful ordinance. A preacher who devotes his whole time and strength to the service of the Church of God from twenty to fifty or sixty years of age, should be then excused from his severer labor, and maintained at the charge of the sanctuary. This would not only be a great comfort to a worn-out servant of God, but also of great use to the work of the ministry, which, to be faithfully and effectually performed, requires all the powers of the body and mind of man. Old faithful ministers are to be highly respected for their work's sake, and to be supplied with all the necessaries and comforts of life; but how little can they do in the public ministry of the word, however willing to work, when their eye waxes dim and their bodily strength fails! See Numbers 8:25. Both for their own sakes, and for the good of the Church, they should be excused from a labor to which they must be almost every way inadequate. But notwithstanding this comparative inactivity, their counsels, advice, and experience will always be considered as a treasure to the Church of Christ

From (a) thirty years old and upward even until fifty years old, all that enter into the host, to do the work in the tabernacle of the congregation.
(a) The Levites were counted at three times, first at a month old when they were consecrated to the Lord, next at 25 years old when they were appointed to serve in the tabernacle, and 30 years old to bear the burdens of the tabernacle.

From thirty years old and upward even until fifty years old,.... This is the full time of the Levites service, and the prime season of man's life for business; at thirty years of age he is at his full strength, and when fifty it begins to decline: it is said in the Misnah (x),"a son of thirty years for strength,''upon which one of the commentators (y) makes this remark, that the Levites set up the tabernacle and took it down, and loaded the wagons, and carried on their shoulders from thirty years and upwards: thus both John the Baptist, the forerunner of Christ, and Christ himself, entered into their ministry at this age:
all that enter into the host; army or warfare; for though the Levites were exempted from going forth to war, yet their service was a sort of warfare; they were a camp of themselves about the tabernacle, and part of their work was to watch and guard it, that it was neither defiled nor robbed; in allusion to this, the ministry of the word is called a warfare, and ministers of the Gospel good soldiers of Christ, and their doctrines weapons of warfare, 1-Timothy 1:18; some interpret this of the troop, company, or congregation of the Levites, which a man of thirty years of age was admitted into for business:
to do the work in the tabernacle of the congregation; not in the sanctuary, either in the holy place or in the most holy place, where they were never allowed to enter, or do any business in, such as sacrificing, burning incense, &c. but in that part of it which was called "the tabernacle of the congregation", or where the people assembled on occasion, and that was the court, which was so called, as Jarchi observes on Exodus 29:32.
(x) Pirke Abot, c. 5. sect. 21. (y) Bartenora in Pirke Abot, c. 5. sect. 21.

From thirty - This age was prescribed, as the age of full strength of body, and therefore most proper for their laborious work of carrying the parts and vessels of the tabernacle, and of maturity of judgment, which is necessary for the right management of holy services. Whence even John and Christ entered not upon their ministry till that age. Indeed their first entrance upon their work was at their 25th year, when they began as learners, and acted under the inspection and direction of their brethren; but in their 30th year they were compleatly admitted to a full discharge of their whole office. But David, being a prophet, and particularly directed by God in the affairs of the temple, made a change in this matter, because the magnificence of the temple, and the great multitude of sacred utensils and sacrifices, required a greater number of attendants than formerly was necessary. Until fifty - When they were exempted from the toilsome work of carrying burdens, but not discharged from the honourable and easy work done within the tabernacle, Numbers 8:26. All that enter - That is, that do and may enter, having no defect, nor other impediment.