Commento su Esodo 26:23

ושני קרשים תעשה למקצעת AND TWO BOARDS SHALT THOU MAKE FOR THE CORNERS — one for the north-west corner and one for the south-west corner. All the eight boards were set in a row, only that the entire width of these two did not show in the interior of the Tabernacle, but only a half cubit on the one side and a half cubit on the other side could be seen in the interior, thus making up the breadth to ten cubits. The remaining cubit of one board and the remaining cubit of the other board came against the cubit thickness of the boards of the Tabernacle on the north and the south sides, so that the outside should be even.

Against the amoh thickness of the northern and southern mishkon planks. [Rashi knows this] because [the dimensions of the mishkon] is derived from the Beis Hamikdash, whose width (twenty amohs) was one-third of its length (sixty amohs). So too with the mishkon: its width [ten amohs] was one-third of its length (thirty amohs).