1 Kings 6:20

And the oracle, this room, in the forepart, was twenty cubits in length and twenty cubits in breadth and twenty cubits in the height thereof, a perfect cubical space, which may have had an unused attic room, if the Sanctuary was thirty cubits high over its entire length; and he overlaid it with pure gold, in the form of thin sheets; and so covered the altar, which was of cedar, this being the altar of incense, which stood against the immediate wall of the Most Holy Place and was almost considered a part of its equipment, Exodus 30:6; Exodus 40:5.