What purpose did the cover of Tachash-skin, which covered all the holy vessels, serve?
Ramban: To protect the holy vessels from the rain. 1
Perhaps, bearing in mind its beautiful colors, 2 it was for Hidur Mitzvah.
Why, in contrast to all the other holy vessels, was the Tachash-skin on the Aron covered with a cover of Techeiles?
Ramban #1: In deference to the holy Aron, it was covered first by the Paroches (its own curtain), then by the Tachash-skin, to protect it from the rain, 1 and on top, by a cover of Techeiles - that one should see an honored garment of Techeiles, that resembled 'the very heaven in purity'.
Ramban #2 (citing the Ibn Ezra): The Pasuk means that they placed the cover of Techeiles on top of the Aron and the Paroches, and a cover of Tachash-skin on top of that.
Oznayimla'Torah: Undereneath the Techeiles cover, due to the principle 'Ein Somchin al ha'Neis' - but not on top, because the Aron, which 'carried those who carried it', did not require protection.
What is the meaning of "ve'Samu Badav"?
Ramban #1, Ibn Ezra #1, and Moshav Zekenim #1: It means that they placed the staves on the shoulders of those who carried it (on the shoulders of the Kohanim - Ramban). 1
Ramban #2 and Moshav Zekenim #2: It means that they arranged the staves 2 in the rings in order to transport the Aron. 3
Moshav Zekenim #3 (on Pasuk 8): Two poles were permanently fixed in [two rings of] the Aron. The Torah teaches us here that when they needed to carry it, they inserted two other poles [in two other rings].
Moshav Zekenim #4 (on Pasuk 8): There were grooves in the poles. When they needed to carry the Aron, they inserted the rings into the grooves.
Ibn Ezra #2: They removed the staves when putting the cover on, and now they returned them. 4
See both sets of notes in R. Chavel's commmentary).
Da'as Zekenim (on Pasuk 5) ? it cannot mean that they placed them in the rings, since the Torah writes "Lo Yasuru Mimenu!", prohibitting their removal - ever.
Kesef Mezukak (in R. Chavel's footnotes): When the Mishkan was erected, the poles extended to the Paroches. When they carried it, they were half in front and half in the back.
The Ibn Ezra (in Terumah, Sh'mos 25:15) holds that "Lo Yasuru Mimenu" does not apply when covering the Aron.
Why does the Torah write "Vesamu Badav" by the Aron and the Mizbe'ach ha'Nechoshes and "Ve'samu Es Badav" by the Shulchan and the Mizbe'ach ha'Zahav?
Oznayim la'Torah: Based on the fact that each of the two poles of the Aron and the Mizbe'ach ha'Nechoshes were placed into two rings, whereas the four poles of the Shulchan 1 and the two of the Mizbe'ach ha'Zahav were each placed into one ring, the former were put in place when they they were made and never removed, whereas the latter - seeing as a pole does not stand well in one ring unless it is being carried by two people - were only fitted each time before they traveled. Consequently, the Torah writes "Vesamu es Badav" by the Shulchan and the Mizbe'ach ha'Zahav, indicating that they now placed the poles into the rings, and "Vesamu Badav" by the Aron and the Mizbe'ach ha'Nechoshes, since they only needed to arrange the poles but not to place them. 2
Why does the Torah say "es Badav" regarding the Shulchan and the gold Mizbe'ach, but not regarding the Aron and Mizbach ha'Olah?
Moshav Zekenim citing R. Yehudah ha'Chasid: In the Aron and Mizbach ha'Olah, the plating (Batim) on the poles was fixed in the rings. They inserted [or fixed] the poles themselves, without the Batim. In the Shulchan and the gold Mizbe'ach, the Batim were on the poles. "Es" teaches that they inserted the poles with the Batim. 1
Moshav Zekenim: What was Betzalel's source to make Batim? He was not commanded in Parshas Terumah! At the time of the command, it says "Es"(regarding the poles of all of them) to include the Batim. "Es" is not repeated [regarding the poles of the Aron and Mizbach ha'Olah], for they were left permanently in the rings.
