Exodus 26:21 KJV

19And thou shalt make forty sockets of silver under the twenty boards; two sockets under one board for his two tenons, and two sockets under another board for his two tenons.

20And for the second side of the tabernacle on the north side there shall be twenty boards:

21And their forty sockets of silver; two sockets under one board, and two sockets under another board.

22And for the sides of the tabernacle westward thou shalt make six boards.

23And two boards shalt thou make for the corners of the tabernacle in the two sides.