1 Chronicles 23:30

And to stand every morning to thank and praise the LORD, and likewise at even;

And to stand every morning ... to perform all the requisite functions of sacred officials. The number of 38,000 Levites, exclusive of priests, was doubtless more than sufficient for the ordinary service of the tabernacle. But this pious king thought that it would contribute to the glory of the Lord to employ as many officers in His divine service as possible. These first rules, however, which David instituted, were temporary, as very different arrangements were made after the ark had been deposited in the tabernacle of Zion.