The central crossbar in the middle of the frames shall extend from one end to the other.
Very particular directions are here given about the boards of the tabernacle, which were to bear up the curtains, as the stakes of a tent which had need to be strong, Isa 54:2. These boards had tenons which fell into the mortises that were made for them in silver bases. God took care to have every thing strong, as well as fine, in his tabernacle.
Commenting on Exodus 26:15-30
And thou shall rear up the tabernacle,.... When thus finished, and all the furniture belonging to it completed: according to the fashion thereof, which was showed thee in the mount; this is the third time that this is observed to Moses in the account of the tabernacle; which shows how punctually God would have the pattern observed he had given him, and that all things...
Exo 26:28-29 “And the middle bar in the midst of the boards (i.e., at an equal distance from both top and bottom) shall be fastening (מבריח) from one end to the other.” As it thus expressly stated with reference to the middle bar, that it was to fasten, i.e., to reach along the walls from one end to the other, we necessarily conclude, with Rashi...
Commenting on Exodus 26:28-29