פירוש על שמות 26:24

ויהיו AND THEY SHALL BE — all the boards shall be —תאמים COUPLED TOGETHER with each other, מלמטה BENEATH, so that the thickness of the edges of two adjacent sockets should not form a space between them, keeping them apart. That is what I meant when I explained (v. 17) that the pivot-like tenons of a board should be cut away on all sides, in order that the breadth of the board shall project at the sides beyond the tenons of the boards that it may cover the rim of the socket. In like manner was the adjacent board treated. The result was that they coupled together (stood one close against the other). Each end-board in the western row was cut away along its width into its thickness over against the portion cut away from the adjacent boards of the northern and southern wall, so that the sockets standing between should not part them (the end-board and that standing next to it on the north side or south side).

AND THEY SHALL BE COUPLED TOGETHER ABOVE THE HEAD OF IT UNTO THE ONE RING. According to Rashi’s interpretation this verse goes back to explain that all the boards should be coupled together beneath, where the boards were cut away on their sides, and they all should be coupled together about the head of it, meaning “of each board.” Or it may be that rosho (the head of it) refers to the top of the Tabernacle. Similarly, [according to Rashi] the expression unto the one ring means of each of the boards. Likewise he explained, thus shall it be for them both,²²³In the second half of Verse 24 (before us). for the two end boards [for the board at the end of the north side and for the adjacent board in the western wall].
But if this is so, I do not know why Scripture does not explicitly tell us about these rings, saying “and you shall make twenty gold rings” [instead of saying, unto the one ring, which means of each board], seeing that it mentions the cut which he is to make in all the boards.²²⁴Verse 17. Moreover, how could Scripture say unto the one ring with the definite article [when it has not mentioned it previously]? Perhaps because it is the customary manner with all houses made of boards to attach them at the top with one ring, Scripture shortened the explanation and said the ring — meaning the one which is known to him and customary. Similarly it said of the bars, and thou shalt make their rings of gold for places for the bolts,²²⁵Verse 29. which means the customary [rings] being known to them. A similar case is the expression, their hooks shall be of gold.²²⁶Verse 37.
I have found in the Beraitha on the work of the Tabernacle [the following text]: “He cut away the board at the top, a fingerbreadth on one side and a fingerbreadth on the other side, and he placed them [i.e., the two adjacent boards] inside one gold ring in order that they should not move apart from each other, for it is said, And they shall be coupled together beneath, and they shall be coupled together above the head of it unto the one ring. Now it need not have said, unto the one ring; and what does it teach us by saying it? It is to teach us that this is the place where the bolts were inserted.” Accordingly, the verse stating: and they shall be coupled together above the head of it, refers to the head of the board where it was cut away until the place of the upper ring of the bolts, for the incision in the board was to extend as far as the place of the ring. Now Scripture was not particular [concerning these upper parts of the boards] how they should be attached, whether with rings of silver or gold, fixed ones or moveable, or with connecting rods. But the Beraitha states that Moses made rings for that purpose. However, in line with the plain meaning of Scripture this verse refers only to the endboards.

אל הטבעת האחת, to the ring at the thickest point of the board forming the corner post. [we referred to this in verse 23 where these two boards are described as serving with one cubit in a westerly direction, completing the length of the structure and with the half cubit constituting its thickness closing the gap left on either side of the six boards forming the western wall of the Tabernacle. (compare Rash’bam there) Ed.] The bolts (bars) running alongside the walls were also inserted both in the lower level and the higher level (above the center bar) through the rings attached to these corner boards at the south-west and south-east of the Tabernacle respectively, ensuring that the structure was solid.