ציטירנדיקער פּירוש אויף שמות 26:32

ועמודיו עשרים, “and its pillars twenty.” The Torah fails to mention the raw material these pillars were made of. Presumably, we are to deduce this by comparing them to other pillars, such as the ones at the entrance to the Sanctuary, and the pillars that supported the dividing curtain. These were all made from acacia wood, expressly stated. (26,32) Also the fact that these pillars were overlaid with silver is not mentioned here, although it is mentioned in Parshat Vayakhel, (36,36)

ויעש לה ארבעה עמודי שטים, “he made for it (the dividing curtain) four pillars of acacia wood.” We have explained already on Parshat Trumah 26,32, why the pillars for the dividing curtain and the pillars at the entrance to the Tabernacle were required, and their respective numbers.