Every day there is a completely different illumination, which comes by virtue of the influence of Zeir Anpin, consisting of 6 Sefirot, upon the 7th Sefira, Malchut. Over the course of these “6 days” Malchut becomes corrected and joins Zeir Anpin.
Once all 6 Lights—Hesed, Gevura, Tifferet, Netzah, Hod, and Yesod have influenced Malchut and corrected her, they unite together. This is called the 6th day, Friday. On this day an illumination comes that is made up of all the Lights that were received during the week. This is called Yesod (foundation), after which the Sabbath begins.
On the Sabbath all the previous Lights shine together with one great Light and there is nothing new on our part, from the “awakening from below.” That is why there is no work, discernments, or corrections made on the Sabbath. It is the result of the work done throughout the week, the result of all the preceding clarifications and corrections.
Then an ascent takes place by virtue of this additional illumination, which happens “on the 5th hour of the 6th day of the week,” meaning from the 5th Sefira of the 6th day, because the 6th day, Yesod, contains its own Sefirot: Hesed, Gevura, Tifferet, Netzah, and Hod. This time is the beginning of entering the 7th day, the Sabbath.
This Light brings additional clarification, understanding, and bestowal. This is the addition of the Sabbath called “an additional soul.” This is the reason why the Ari introduced a custom to wear two jackets on the Sabbath instead of one. It symbolizes the fact that a person needs a double screen against the new additional Light that he receives from Above.
This Light influences Kelim or desires and raises them because it is impossible to remain in the same place while receiving Light.
From the 3rd part of the Daily Kabbalah Lesson 2/16/11, Talmud Eser Sefirot