The Torah says simply that God finished His work by the seventh day. Targum Pseudo-Jonathan on (Genesis 2:2) smuggles in one of Judaism's most famous traditions: "the ten formations which He had created between the suns."
"Between the suns" — bein ha-shmashot — is the twilight moment between sunset on the sixth day and the arrival of Shabbat. In that sliver of time, Pirkei Avot 5:6 (c. 200 CE) teaches, God created ten special things: the mouth of the earth that later swallowed Korach, the mouth of Miriam's well, the mouth of Balaam's donkey, the rainbow, the manna, Aaron's rod, the shamir worm, the shape of the written letters, the writing, and the Tablets themselves.
The Targumist is telling us that Shabbat did not arrive in an empty room. God packed the last possible seconds of the workweek with the tools that later miracles would require. Every supernatural intervention in Torah history was already manufactured before the first candle of the first Shabbat was lit.
Then rest. The world was finished, and so was the rushing. The seventh day began not because there was nothing left to do, but because God chose to stop.