Above All Else

Even for the greatest cause, you can't violate Shabbos (except to save a life).

And building the Tabernacle, a home for HaShem, is one of the greatest causes there is.

Especially since its construction was a rectification for the sin of the Golden Calf, and the Divine presence resting there was proof that HaShem had forgiven the Jewish people for the Golden Calf.

And when involved in such a great cause it's easy to justify overlooking another mitzvah or value, in the name of the cause.

That's why the commandment to build the Tabernacle is preceded by a reminder about keeping Shabbos, to remind you that even building the Tabernacle doesn't take precedence over Shabbos .

"Six days work may be done, but the seventh day shall be holy for you, a day of complete rest for HaShem." Exodus 35:2