שמות ל:ד פירוש: רש״י, ספורנו, Siftei Chakhamim וRav Hirsch

צלעתיו Here this word must signify “corners” (not “sides” as Rashi explains in Exodus 25:12), as it is translated in the Targum, since it is stated afterwards, על שני צדיו, “upon the two sides of it”, so that the phrases mean, “the two corners that are on its two sides”.

שתי צלעותיו, at the upper corners.

Here it has the meaning of “corners”. . . Although everywhere else it means “side.”