Part 15 · Chapter 59

And this is the reason that Shabbat is called actual holiness (Kodesh), as it is written: “And you shall keep the Shabbat, for it is holy to you.” But the festivals are called “holy convocations” (Mikraei Kodesh), because on the day of Shabbat ZA receives from the holiness of AVI and gives her share to the Nukva through him. And it is found that ZA himself, who is the aspect of the day of Shabbat, is called actual holiness; but the rest of the festivals do not ascend to the place they ascend on the day of Shabbat, but on every festival they ascend according to their aspect, as said.