Sforno on Exodus 31:14/ספורנו על שמות ל״א:י״ד

1ושמרתם את השבת, there is yet another reason why the Sabbath regulations must not be overridden for the sake of completing the Tabernacle sooner;

2כי קדש היא לכם, מחלליה מות יומת, the Sabbath is not only a holy day for you, i.e. it is not only a positive commandment to observe it, but is also a most important negative commandment, so much so that deliberate violation, desecration of it sanctity, is punishable by death. Seeing that building the Tabernacle is only a positive commandment, it is clear that a positive commandment cannot override something that is both a positive and a negative commandment.

3כל העושה בה מלאכה ונכרתה הנפש ההיא, another reason for not desecrating the Sabbath in order to carry on with the building of the Tabernacle is the extremely heavy penalty associated with deliberate violation of the laws of the Sabbath. The reason for such a penalty is that anyone violating the concept of the Sabbath prohibitions thereby denies that I, G’d, created the universe out of no preexisting tangible substance. Anyone desecrating the Sabbath deliberately would never benefit from the existence of a building such as the Tabernacle. How could he claim a share in the G’d Who dwells in this Tabernacle?

4מקרב עמיה, from those members of his people who are destined to live on in the world to come after their bodies are left behind on earth by their souls.