Exodus 38:5-7

King James Version

⁵ And he cast four rings for the four ends of the grate of brass, to be places for the staves.

⁶ And he made the staves of shittim wood, and overlaid them with brass.

⁷ And he put the staves into the rings on the sides of the altar, to bear it withal; he made the altar hollow with boards.