4:1-3 The middle-aged men of the tribe of Levi, all from thirty years old to fifty, were to be employed in the service of the tabernacle. The service of God requires the best of our strength, and the prime portion of our time, which cannot be better spent than to the honour of Him who is the First and Best. And the service of God should be done when we are most lively and active. Those do not consider this who put off repentance to old age, and so leave the best work to be done in the worst time.

Verse 2. - Take the sum of the sons of Kohath. The Levites having been separated from the other tribes, the Kohathites are now to be separated from amongst the other Levites for the most honourable and sacred duties. To them the preference was given presumably because the priests were Kohathites.

Take the sum of the sons of Kohath from among the sons of Levi,.... They were to begin with them first, and number them:

after their families, by the house of their fathers; as many as were of the age after mentioned; and the reason why they began with Kohath, and not Gershon, the eldest son, as in the former numbering, was; not as Aben Ezra suggests, because of Moses and Aaron, who sprung from him, for that, if it had any strength in it, would have held good before; but rather, as Chaskuni and others, because the Kohathites carried the ark and other holy things; though the true reason seems to be, because of the order observed in taking down the tabernacle, and removing the parts of it, and the things in it; and it was most proper and reasonable, when they were about to take it down, first to take out the ark, table, &c. which was the business of the Kohathites to carry; next to take down the curtains, coverings, and hangings for the tabernacle and court, and the doors thereof, which were the charge of the Merarites; wherefore, in this order the sum out of each of them fit for business were ordered to be numbered.

Numbers 4:2 Parallel Commentaries
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