Parshios Vayakhel and Pekudei

(The Segulah of Learning Zera Shimshon)

Vayakhel

Rashi tells us that Moshe Rabbeinu tells Bnei Yisroel about the prohibition of working on Shabbos before the mitzvah of building the Mishkan to let them know that construction of the Mishkan, work of the Mishkan, does not override Shabbos.

The question is, why would we think that work of the Mishkan would overrule the laws of Shabbos?

The Zera Shimshon explains that without Rashi's insight it might seem that since the work in the Mishkan is done on Shabbos, if one of the keilim needs to be repaired (to enable the work of the Mishkan, for example, to help the kohanim in karbanos offerings), it should be done on Shabbos too.

Therefore, the Torah tells us about Shabbos before Mishkan to make sure we realize that the work of the Mishkan does not override Shabbos.

Pekudei

The Midrash in Yalkut, (Melachim 184) tells us that R' Chanina says that the work of the Mishkan was completed on the 25th of Kislev, but Hashem delayed the erection of the Mishkan until the month of Nissan when Yitzchak Avinu was born. 

The Zera Shimshon asks why it is significant that the Mishkan was completed on the 25th of Kislev. Also, why did they delay putting up the Mishkan when they had hastened to construct it? Lastly, what does Yitzchak Avinu have to do with the Mishkan?

Rabbeinu Bachya writes that the Mishkan's construction corresponds to the creation of the world. 

The creation of the world took 72 hours: 6 days multiplied by 12 hours (as only the daytime hours are counted). The construction of the Mishkan took 72 days. (There were also 72 letters on the Choshen, also corresponding to the 72 letters of Hashem's name.) 

The calculation of the amount of days it took is as follows: Moshe Rabbeinu came down from the har on Yom Kippur and commanded the Jews to build the Mishkan. That's 20 days left in Tishrei, 29 in Cheshvan, 25 in Kislev. That equals 74 days, and then we subtract 2 days spent on collecting donations, ending with 72 days total spent on building the Mishkan. (We include Shabbos in this calculation, because although they didn't build on Shabbos, they spent Shabbos learning the halachos they needed to know to do this work.)

This is why the date of 25 Kislev is significant –– letting us know that the building of the Mishkan corresponds to the creation of the world and the letters of Hashem's name. Why then was the final erection delayed until the birth month of Yitzchak Avinu?

The Gemara in Shabbos (89b) tells us that both Avraham and Yaakov felt that Bnei Yisroel should be destroyed for their sins. However, Yitzchak Avinu felt that Hashem should show Bnei Yisroel mercy and take out His wrath k'vyachol on the Beis Hamikdash instead. (The Mishkan was called as such from the root "mashkon," collateral. It was literally collateral for the sins of Klal Yisroel.) Because Yitzchak played this role in making this suggestion, Hashem waited until this month that Yitzchak was born to show that He accepted Yitchak's argument. In the future, the Beis Hamikdash would serve as collateral for Klal Yisroel's sins, shielding them from destruction.

Source: Zera Shimshon Parshios Vayakhel, Pekudei