Exodus 36:22-24

Amplified Bible

²² Each board had two tenons (dovetails), fitted to one another; he did this for all the boards of the tabernacle. ²³ And [this is how] he made the boards [for frames] for the tabernacle: twenty boards for the south side; ²⁴ and he made under the twenty boards forty silver sockets; two sockets under one board for its two tenons (dovetails), and two sockets under another board for its two tenons.