Exodus 30:2
2
A cubit shall be the length thereof, and a cubit the breadth thereof; foursquare shall it be: and two cubits shall be the height thereof: the horns thereof shall be of the same.
Door and lintel
In 1 Kings 6:31, this signifies the introduction of truth to good and the conjunction of such truth with good. (Arcana Coelestia 8989)