Over the table of the Presence they are to spread a blue cloth and place the plates and cups on it, along with the bowls and pitchers for the drink offering. The regular bread offering is to remain on it.
We have here a second muster of the tribe of Levi. As that tribe was taken out of all Israel to be God's peculiar, so the middle-aged men of that tribe were taken from among the rest to be actually employed in the service of the tabernacle. Now observe, I. Who were to be taken into this number. All the males from thirty years old to fifty.
Commenting on Numbers 4:1-20
And upon the table of shewbread they shall spread a cloth of blue,.... That that also might not be seen nor touched by the Levites: and put thereon the dishes, and the spoons, and the bowls, and the covers to cover withal: all which belonged to the shewbread table; the use of which; see Gill on Exo 25:29; these seem to be put not immediately...
continual showbread--Though the people were in the wilderness fed upon manna, the sacred loaves were constantly made of corn, which was probably raised in small quantities from the verdant patches of the desert.