1. Rashi 26:15 writes that the atzei shitim used to make the mishkan came from trees that Ya'akov Avinu had planted in Egypt which Bnei Yisrael took with them when they left. R' Ya'akov Kaminetzki in Emes l'Ya'akov explains that what Ya'akov Avinu planted was not trees for wood -- in the 210 years (which had the potential to be 400 years) until they left Egypt Bnei Yisrael could have managed to find some other wood to take. What Ya'akov Avinu planted was hope. To simply tell Bnei Yisrael that one day there would be a geulah would not have made much of an impression. To take action, to plant in anticipation of the geulah, showed them that it was real. (The lesson for us in that simply talking about the beauty of Torah is not enough. We have to act on that belief and live it.)
Ibn Ezra at the beginning of Terumah challenges Rashi based (among other things) on a pasuk from our parsha. The Torah writes, "...v'chol asher nimtza ito atzei shitim l'chol milechas ha'avodah hei'vi'u." (35:26) The term "nimtza ito" means the wood belonged to those people. It was theirs and they were donating it of their own accord -- it wasn't something that Ya'akov had prepared beforehand just for use in the mishkan.
It sounds like the machlokes Rashi and Ibn Ezra revolves around where to place the comma in the pasuk. Ibn Ezra read it like this: "...v'chol asher nimtza ito atzei shitim," whoever has wood, COMMA, "l'chol milechas ha'avodah hei'vi'u," brought it for the holy work. Rashi, however, may have read it like this: "...v'chol asher nimtza ito atzei shitim l'chol milechas ha'avodah," whoever was entrusted to keep with them wood that was meant to be used [as designated by Ya'akov] for the mishkan, COMMA, "hei'vi'u," they brought it.
2.When there was no longer a need for donations for the Miskhan, the parsha tells us that an announcement went out, "al ya'asu od melacha." When the people heard that, "va'yikaleh ha'am mei'havi," the people stopped bringing donations. Meforshim (see Seforno, Rashbam, Chizkuni) are medayek that the announcement did not say not to bring anything, but rather not to make anything. Ksav Sofer explains this based on the din that hazmanah lav milsa hi, designating an item for some use has no halachic effect unless some action was taken in making the item or in using the item for that purpose (see Sanhedrin 47). It's only if something was made for the sake of the mishkan that it would become assur; therefore, the call went out to stop making things. The people understood on their own that this meant nothing new was needed, and so they stopped bringing as well.
I'm a little confused. True, hazmanah lav milsa, but there is another din of amiraso l'gavoha k'mesiraso l'hedyot, that pledging something for hekdesh use makes it the property of hekdesh. Had something been brought to the mishkan, even if not made for use there, wouldn't it become property of the mishkan by virtue of amiraso l'gavoha? Shouldn't the people have been told to stop bringing things lest the extra become property of the mishkan by virtue of amiraso l'gavoha?
P.S. Apologies for not getting to respond to comments on last week's post.