Likutei Moharan 11:5/ליקוטי מוהר"ן י״א:ה׳

15. Guarding the brit has two levels. There is the person whose marital relations are during the six days of the week. Even so, he guards his brit as the Torah requires, because he does not transgress the Torah’s laws. And there is the person who guards the brit in that his marital relations are [only] from Shabbat to Shabbat.

2These [two levels] correspond to the upper unification and the lower unification. There is the aspect of Shadai of Shabbat: [When God reached the Shabbat of Creation,] He said to His world, “Dai! (Enough!)” (Chagigah 12a), restricting Himself from all works. This corresponds to the upper unification.

3There is also the aspect of Shadai of the weekdays. For even on the weekdays there are restrictions, from one work to the next. This corresponds to Metat, whose rule is the six days of the week, corresponding to the six orders of the Mishnah (Tikkuney Zohar #18). For [Metat’s] name is like that of his Master’s, as is written (Exodus 23:21), “because My Name is in him.” This is the lower unification. In other words, the Holy One, blessed-be-He, clothes Himself in Metat during the six days of the week and rules the world through him.