Exodus 26:17-19

King James Version

¹⁷ Two tenons shall there be in one board, set in order one against another: thus shalt thou make for all the boards of the tabernacle.

¹⁸ And thou shalt make the boards for the tabernacle, twenty boards on the south side southward.

¹⁹ 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.