Exodus 26:23 (KJV)

And thou shalt make the boards for the tabernacle, twenty boards on the south side southward.

And 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.

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

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

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

And they shall be coupled together beneath, and they shall be coupled together above the head of it unto one ring: thus shall it be for them both; they shall be for the two corners.

And they shall be eight boards, and their sockets of silver, sixteen sockets; two sockets under one board, and two sockets under another board.

And thou shalt make bars of shittim wood; five for the boards of the one side of the tabernacle,

And five bars for the boards of the other side of the tabernacle, and five bars for the boards of the side of the tabernacle, for the two sides westward.

And the middle bar in the midst of the boards shall reach from end to end.