Be'er Mayim Chaim, Genesis 2:2/באר מים חיים·בראשית ב׳:ב׳

1On the seventh day God finished the work that He had been doing, and He rested on the seventh day, etc.: Meaning God surely completed and finished all of the work on the seventh day. But with what? "And He ceased on the seventh day" - with this, that He rested, and He made it into a day of rest and joy, which was the end of the thought of creating the entire work of the heavens and the earth. It is with this that He finished and accomplished the end of their making. And with this, the words of our Rabbis about this verse are sweetened (Bereishit Rabbah 10:9): Geniva said, "This is analogous to a king who made himself a wedding canopy, painted it and embossed it. What was it lacking? A bride to enter it. So, too, what was the world lacking? Shabbat," etc. To here [is the midrash]. The commentators there were hard-pressed to explain what the world was missing without Shabbat. But according to our words, it is very correct, since the Shabbat to the world is exactly like a bride to the wedding canopy. For the entire existence of the world was only created to prepare the meal and the joy of the Shabbat day. And before the Shabbat day arrived, everything was lacking. So the seventh day completed and finished the work, the packed day of joy. Then the bride went up to the wedding canopy, as mentioned.

2And behold, Rashi, may his memory be blessed, on the Torah on this verse, cites the words of this midrash, but he changed its wording. And he wrote, "What was the world lacking? Rest, etc." And according to how it appears, he is explaining the words of the midrash as follows: What was the world missing? Shabbat, meaning rest. And likewise did the Matanot Kehunah write that this was the intent of Rashi, may his memory be blessed. And this, too, corresponds to our words. And its explanation was that the whole world was lacking in its work from the angle that there was no rest in it. But the essence of the creation was to do good to the creatures with rest and joy. So the work [of creation] was not complete until Shabbat arrived and rest came to the world. So the Holy One, blessed be He, rested and enlightened the world with His great goodness. And through this, He also attained great pleasure from His world that He created. And He and all of the worlds were at peace and had great delight. And that is why He said [...]