Why is the prohibition against doing work on Shabbat written prior to the instruction for building the Mishkan?
35:2 Work shall be done for six weekdays, but the seventh day must be a holy day for you, a Sabbath of Sabbaths to HASHEM. Whoever does any work on it shall be put to death.
Moshe warned the Benei Yisrael that they must keep the Shabbat. They should not think that they were to complete the Mishkan as quickly as possible and that in doing so it was permissible to violate the Shabbat. They had to realize that even in making the Mishkan they were only to work six days. Keeping the Shabbat is a very important thing. Anyone violating it by doing work was to be put to death by stoning.
Moshe began by saying, "These are the things that G-d has commanded you to do." "These are the things" is in the plural, which is difficult to understand; Since the Torah is speaking of the Shabbat, Moshe should have said, "This is the thing," in the singular.
It is impossible to say that the plural "these are the things" includes both the commandment of the Shabbat and the work of the Mishkan. The Torah introduces the work of the Mishkan by saying, "This is the thing that G-d commanded." (35:4) Therefore, when Moshe said, "These are the things," he was speaking about the Shabbat alone. He should have said, "This is the thing," using the singular.
However, Moshe said to the Benei Yisrael, "Do not think that in order to keep the commandment of the Mishkan, to finish it as soon as possible, you are permitted to violate the Shabbat; rather, you must realize, 'These are the things that G-d has commanded you to do.' G-d has commanded you to do two things. You must keep the Shabbat as well as build the Mishkan. It is forbidden to violate the Shabbat for the sake of the Mishkan."
There are 39 categories of work that are forbidden on the Shabbat.
Sowing
Plowing
Reaping
Binding sheaves
Threshing
Winnowing
Selecting
Grinding
Sifting
Kneading
Baking
Shearing wool
Washing wool
Beating wool
Dyeing wool
Spinning
Weaving
Making two loops
Weaving two threads
Separating two threads
Tying
Untying
Sewing two stitches
Tearing
Trapping
Slaughtering
Flaying
Salting meat
Curing hide
Scraping hide
Cutting hide up
Writing two letters
Erasing two letters
Building
Tearing a building down
Extinguishing a fire
Kindling a fire
Hitting with a hammer
Taking an object from the private domain to the public, or transporting an object in the public domain. (Mishnah - Shabbat 7:2)
Sowing
Plowing
Reaping
Binding sheaves
Threshing
Winnowing
Selecting
Grinding
Sifting
Kneading
Baking
Shearing wool
Washing wool
Beating wool
Dyeing wool
Spinning
Weaving
Making two loops
Weaving two threads
Separating two threads
Tying
Untying
Sewing two stitches
Tearing
Trapping
Slaughtering
Flaying
Salting meat
Curing hide
Scraping hide
Cutting hide up
Writing two letters
Erasing two letters
Building
Tearing a building down
Extinguishing a fire
Kindling a fire
Hitting with a hammer
Taking an object from the private domain to the public, or transporting an object in the public domain. (Mishnah - Shabbat 7:2)
We derive these categories of work from the types of work needed to make the Mishkan. We see that the commandment regarding the Shabbat comes immediately before the Mishkan. We thus learn that the types of work that were needed to build the Mishkan are precisely the ones that are forbidden on the Shabbat.
Moshe therefore said, "These are the things that G-d has commanded you to do; six days do work... 'These things' refers to the 39 categories of work that I commanded you to do in the Mishkan. These may be done during the six weekdays. On the seventh day however, it is forbidden for you to do them."
- Me'am Lo'ez
