1 Kings 8:6

And he built twenty cubits on the rear part of the house with boards of cedar from the floor to the ceiling; he built them for it on the inside as an inner sanctuary, as the Holy of Holies.

“Now give your heart and your soul to seek Yahweh your God; arise, therefore, and build the sanctuary of Yahweh God, so that you may bring the ark of the covenant of Yahweh and the holy vessels of God into the house that is to be built for the name of Yahweh.”

Then Solomon assembled the elders of Israel and all the heads of the tribes, the leaders of the fathers’ households of the sons of Israel to Jerusalem, to bring up the ark of the covenant of Yahweh from the city of David, which is Zion.

He measured its length, twenty cubits, and the width, twenty cubits, before the nave; and he said to me, “This is the Holy of Holies.”