Exodus 26:17-19

New King James Version

¹⁷ Two ^[a]tenons shall be in each board for binding one to another. Thus you shall make for all the boards of the tabernacle. ¹⁸ And you shall make the boards for the tabernacle, twenty boards for the south side. ¹⁹ You shall make forty sockets of silver under the twenty boards: two sockets under each of the boards for its two tenons.