2. Mose 26:28

"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 and others, that the other four bars on every side were not to reach the whole length of the walls, and may therefore suppose that they were only half as long as the middle one, so that there were only three rows of bars on each wall, the upper and lower being composed of two bars each.

Moses here receives instructions, I. Concerning the inner curtains of the tent or tabernacle, and the coupling of those curtains (Exo 26:1-6). II. Concerning the outer curtains which were of goats' hair, to strengthen the former (Exo 26:7-13). III. Concerning the case or cover which was to secure it from the weather (Exo 26:14). IV. Concerning the boards which were to be reared up to support the curtains, with their bars and sockets (v. 15-30). V. The partition between the holy place and the most holy (Exo 26:31-35). VI. The veil for the door (Exo 26:36, Exo 26:37). These particulars, thus largely recorded, seem of little use to us now; yet, having been of great use to Moses and Israel, and God having thought fit to preserve down to us the remembrance of them, we ought not to overlook them. Even the antiquity renders this account venerable.