Ezekiel 41:4-6

New Catholic Bible

⁴ Beyond the nave, he measured the length of the inner sanctuary, which was twenty cubits, and its width, which was also twenty cubits, after which he said to me, “This is the Holy of Holies.”

⁵ Then he measured the wall of the temple, which was six cubits thick. The width of the side chambers was four cubits all around the temple. ⁶ The side chambers were on three levels, one above the other, with thirty chambers on each level. There were ledges all around the wall of the temple that were designed to serve as supports for the side chambers, but there were no supports in the wall of the temple itself.