1 Chronicles 15:2

Then David said
Either within himself, or to his ministers and courtiers about him:

none ought to carry the ark of God but the Levites;
he saw his former mistake in employing those that were not Levites in bringing up the ark from Kirjathjearim, and bringing it in a cart, and not on the shoulders of the Levites, and so miscarried in his attempt, ( 2 Samuel 6:1 ) and, perhaps, had since more diligently consulted the law of God about this matter:

for them hath the Lord chosen to carry the ark of God, and to minister
unto him for ever;
as long as the Levitical dispensation lasted, as appears from ( Numbers 1:50 ) ( 4:15 ) ( 7:9 ) .