Why does the warning at the beginning of Vayakhel about Shabbat observance mention work that is done on weekdays? And why is the prohibition against kindling fire on Shabbat specificlly singled out in that warning?

Rabbi Dunner introduces a lively and quite hilarious debate between Ibn Ezra and an unnamed Karaite, concerning the Karaite view regarding the use of fire on Shabbat. And he also discusses why it was inappropriate to construct the Mishkan on Shabbat.

VAYAKHEL 2015 – SOURCE SHEET

Image: Ancient Karaite manuscript