Commentary on the Bible, by Adam Clarke, [1831], at sacred-texts.com
David makes Solomon king, Ch1 23:1. Numbers the Levites, and appoints them their work, Ch1 23:2-5. The sons of Levi, Gershom, Kohath, Merari, and their descendants, Ch1 23:6-12. The sons of Amram, and their descendants, Ch1 23:13. The sons of Moses, and their descendants, Ch1 23:14-24. David appoints the Levites to wait on the priests for the service of the sanctuary, Ch1 23:25-32.
David was old and full of days - On the phrase full of days, see the note on Gen 25:8.
Thirty years and upward - The enumeration of the Levites made in the desert, Num 4:3, was from thirty years upwards to fifty years. In this place, the latter limit is not mentioned, probably because the service was not so laborious now; for the ark being fixed they had no longer any heavy burdens to carry, and therefore even an old man might continue to serve the tabernacle. David made another ordinance afterwards; see on Ch1 23:24-27 (note).
Four thousand praised the Lord - David made this distribution according to his own judgment, and from the dictates of his piety; but it does not appear that he had any positive Divine authority for such arrangements. As to the instruments of music which he made they are condemned elsewhere; see Amo 6:5, to which this verse is allowed to be the parallel.
Therefore they were in one reckoning - The family of Shimei, being small, was united with that of Laadan, that the two families might do that work which otherwise belonged to one, but which would have been too much for either of these separately.
To bless in his name - To bless the people by invoking the name of the Lord.
Moses the man of God - "Moses the prophet of God," - T.
To this verse the Targum adds, "The same Jonathan, who became a false prophet, repented in his old age; and David made him his chief treasurer."
But the sons of Rehabiah were very many - The Targum says, "On account of the merits of Moses, the posterity of Rehabiah were multiplied to more than sixty myriads."
Their brethren the sons of Kish took them - This was according to the law made Num 27:1, etc., and Num 36:5-9, in favor of the daughters of Zelophehad, that women who were heiresses should marry in the family of the tribe of their father, and that their estates should not be alienated from them.
Twenty years and upward - It appears that this was a different ordinance from that mentioned Ch1 23:3. At first he appointed the Levites to serve from thirty years and upward; now from twenty years. These were David's last orders; see Ch1 23:27. They should begin at an earlier age, and continue later.
This was not a very painful task; the ark being now fixed, and the Levites very numerous, there could be no drudgery.
Purifying of all holy things - Keeping all the vessels and utensils belonging to the sacred service clean and neat.
Both for the shew-bread - It was the priests' office to place this bread before the Lord, and it was their privilege to feed on the old loaves when they were replaced by the new. Some of the rabbins think that the priests sowed, reaped, ground, kneaded, and baked the grain of which the shew-bread was made. This appears to be a conceit. Jerome, in his comment on Mal 1:6, mentions it in these words: "Panes propositionis quos, juxta traditiones Hebraicas, ipsi serere, ipsi demetere, ipsi molere, ipsi coquere debebatis."
For all manner of measure and size - The standards of all weights and measures were kept at the sanctuary, and by those there deposited all the weights and measures of the land were to be tried. See the note on Exo 30:13.
To stand every morning - At the offering of the morning and evening sacrifice, they sounded their musical instruments, and sang praises to God.
The charge of the sons of Aaron - It was the priests' business to kill, flay, and dress, as well as to offer, the victims, but being few, they were obliged to employ the Levites to flay those animals. The Levites were, properly speaking, servants to the priests, and were employed about the more servile part of Divine worship.