Parshas Vayakhel 5779

Why is Fire Singled Out Regarding Shabbos?

The Torah writes (Exodus 35:3):

On six days work may be done, but on the seventh day you shall have a Sabbath of complete rest, holy to the LORD; whoever does any work on it shall be put to death. You shall kindle no fire throughout your settlements on the Sabbath day.

Rashi (ibid) gives two reasons:

There are some of our Rabbis who say that the law about kindling fire is singled out (more lit., goes forth from the general proposition; i. e. it is specially mentioned here although it is included in לא תעשה כל מלאכה, the law prohibiting all work on Sabbath) in order to constitute it a mere negative command (thus indicating that, like all other negative commands, its infringement is punishable by lashes but does not make the offender liable to death as does the doing of other work on Sabbath). 

and:

Others, however, say that it was singled out in order to separate the various kinds of work comprised in the term כל מלאכה (thus indicating that each transgression of the Sabbath law is to be atoned for separately if several of them have been committed at the same time and under the same circumstances)

Ibn Ezra, the Ramban and the Rashbam explain differently:

Because by the first day and the seventh day of Festival of Matzos [i.e. Pesach] it says "all the work you may not do" to permit אוכל נפש [i.e. work for the personal benefit of people like cooking]. Therefore, now it says regarding Shabbos "you shall not kindle fire" to bake bread and cook meat for fire is אוכל נפש ...

Sforno explains:

even though generally speaking, lighting a fire is not a productive but a destructive activity, seeing that it is an almost indispensable ingredient in most activities the Torah prohibited it as unsuitable for the Sabbath.

Chizkuni, Daas Zkenim and Bechor Shor explain in a similar fashion:

The reason why just the activity of kindling light was chosen by the Torah as the example in question, is that lighting a fire is something that for the onlooker hardly seems like an activity at all, involving neither skill, nor physical strain. If you were to say that granted that actually lighting a fire on the Sabbath is forbidden, but activities preparatory to lighting a fire after the Sabbath are permitted, this too is prohibited. The Sabbath is not a day to be used as a preparation for the activities on the six weekdays. 

Some says that the reason is that just like the fires in Gehinom don't light on Shabbos, the same way we don't light fires on Shabbos

The Talmud (Sanhedrin 35b) explains that this teaches that capital punishment may not be administrated on Shabbos

Spinning Wool While It's Attached

The Torah writes (Exodus 35:26):

And all the women who excelled in that skill spun the goats’ hair.

Rashi writes:

This required extraordinary skill, for they spun it (the goats’ hair) from off the backs of the goats (whilst it was still on the living animals)

The Talmud (Shabbos 99a) adds:

The phrase “whose hearts inspired them” suggests a greater degree of wisdom. Apparently, spinning the goat’s hair curtains required greater skill than spinning the various kinds of wool. And on a similar note, it was taught in abaraita in the name of Rabbi Neḥemya: The hair was rinsed on the goats, and it was even spun from the goats, which required a great deal of skill.

However, while there is a disagreement in in the Talmud (Shabbos 74b) whether one is liable or not if they spin wool that way, the outcome is that it is not, as the Rambam writes (Sabbath 9:7):

One who spins wool from a live creature is exempt – as this is not the way of shearing, nor the way of combing nor the way of spinning.

Fire is Allowed in the Mishkan on Sabbath

Chizkuni and Malbim writes:

in all of your dwellings, i.e. the Tabernacle was exempt from all of these restrictions as it was not a residence for human beings. Communal sacrifices were offered as usual.

Misc:

• A story is cited by the Midrash regarding the Roman emperor and lighting fires on Shabbos
• Karaites don't light fires on Shabbos (see Ibn Ezra here). There is also a discussion regarding Shabbos candles when Karaites and Rabbanites marry.
• Example of wool being spun directly off a sheep with a Navajo spindle