John Gill Commentary Exodus 30:4

"And two golden rings shalt thou make for it under the crown thereof; upon the two ribs thereof, upon the two sides of it shalt thou make them; and they shall be for places for staves wherewith to bear it." — Exodus 30:4 (ASV)

And two golden rings you shall make to it under the crown of
it
The crown was on the top of the altar, at the edge of it all around; and just underneath it were two rings of gold, two on each side:

by the two corners of it, upon the two sides of it you shall make
them ;
at each corner a ring, and at each side; the use of them follows:

and they shall be for places for the staves to bear it with ;
these rings were for the staves to be put into when the altar was to be carried from place to place, as it was in the wilderness, during the travels of Israel there; and this signifies that Christ never leaves his people; when they are in the wilderness he is with them, interceding for them, providing all things necessary for their food, safety, and protection, (Revelation 12:14) .