1 Kings 8:3 - Wesley's Explanatory Notes

The priests — For although the Levites might do this, Numbers 4:15, yet the priests did it at this time, for the greater honour of the solemnity; and because the Levites might not enter into the holy — place, much less into the holy of holies, where it was to be placed, into which the priests themselves might not have entered, if the high — priest alone could have done it.