There are 39 melachot which are prohibited on Shabbat which the sages derived from building the Mishkan.
One commentary points out “building” is a mundane act. When one involves themselves in mundane work, no matter for what meaningful purpose, one can too easily forget why they are doing it. For example, a nurse can take blood all day long and turn into a blood taker, not someone who is helping save lives. Likewise, someone building G-d’s Mishkan can come to look at himself as merely a builder.
Shabbat is a day where we stop and remind ourselves exactly why we are doing it. If we don’t stop and refocus, then even the building of the Mishkan can lose it’s meaning to us.
Logically, Vayakhel should begin by asking Bnei Yisrael for their contributions towards building the Mishkan. However, it begins with a few verses about Shabbat - “six days work shall be done but the seventh day shall be holy for you”. This seems strange since the laws of shabbat were mentioned in greater detail in last weeks parasha - Ki Tisa. Why is it necessary to begin with a brief description of Shabbat rather than to begin by asking for donations towards the Mishkan?
There are many commentaries about this, a more common expression “six days you shall do your work”. The passive verb for doing work suggests a fundamental lesson, the amount of money a person makes is not proportional to the amount of effort one puts in. It is flawed to mentally think that the more work I do the more money I will make. G-d decides how much we all earn. One may have the idea that if one works 7 days a week, they will earn more than if they work 6 days a week. If G-d wants to give us financial success, he can whether we spend 6 or 7 days of effort to earn it. Moshe was requesting for donations. It could have been hard for them to donate because where is this donation coming from?
Moshe uses the expression “six days work shall be done” as it teaches money is earned based on G-d’s wills.
It was first necessary to remove Bnei Yisrael’s anxiety to reassure them that in the final analysis their donations would not cost them anything. As Rambam writes, “no one becomes poor from giving to charity.”
Only after briefly mentioning shabbat, Moshe then asks for contributions for Mishkan.
Based on an idea by Rabbi Yissocher Frand