God’s ceasing to create on the seventh day reflects a stage where the spiritual forces that have descended to the world of action return and ascend to their heavenly source. Likewise, ceasing work on Shabbat enables us to transcend the activities of the six days of the week and return to ourselves, to the soul being connected to its source.

God’s ceasing [His labor] on Shabbat is a metaphor based on human resting from labor.

The term “rest” that is said with regard to the Holy One, blessed be He: “Because on it He rested” (Genesis 2:3), is a metaphor based on a person who rests and ceases the work he has performed. While acting, his mind and thoughts were engaged in the action, and afterward, when he rests, his mind and thoughts return to their source. The deed itself is also contained in his mind, as an element of the action was [already] in his mind in that the action that he was performing was present in his mind [as an intention]. The discharged spiritual force, i.e., the cognitive and conceptual aspect of the action, ascends and returns to become a part of its source, i.e., [divine] cognition and conceptualization. So too, on Shabbat, the force that was extended for the six days of [divine] action via the ten sayings with which the world was created, ascends to the level of thought…

Shabbat resembles repentance, in that both involve the soul returning to its source:

Therefore, Shabbat is made up of the same letters as the word “you shall repent [tashuv],” as the concept of Shabbat and the concept of repentance are one: the return of matters to their source. For repentance is not simply [the rectification of] one’s sins, but rather [the point of repentance] is to restore the soul that has descended very low and has become clothed with materiality to its source, to cleave to Him, may He be blessed. (Rabbi Shneur Zalman of Liadi, Likutei Torah, Deuteronomy 66:3)