C. F. Keil and Franz Delitzsch on Exodus 26:17

Exo 26:17

Every board was to have two ידות (lit., hands or holders) to hold them upright, pegs therefore; and they were to be “bound to one another” (משׁלּב, from שׁלב in Chald. to connect, hence שׁלבּים in 1Ki 7:28, the corner plates that hold together the four sides of a chest), not “pegged into one another,” but joined together by a fastening dovetailed into the pegs, by which the latter were fastened still more firmly to the boards, and therefore had greater holding power than if each one had been simply sunk into the edge of the board.