Another interpretation: "And in all that I have said to you" and so forth (Exodus 23:13). Why is this said? Because it says, "You shall do no manner of work" (Exodus 20:10), from this I know only matters that are primary categories of labor; from where do I learn matters that are forbidden as a measure of rest [decreed by the Sages]? Scripture teaches, "And in all that I have said to you, take heed," to bring in matters that are forbidden as a measure of rest.
Take Heed Reaches Even the Rabbinic Boundaries of Rest
Yalkut Shimoni on Torah 355:2
דָּבָר אַחֵר, וּבְכֹל אֲשֶׁר אָמַרְתִּי וְגוֹ', לָמָּה נֶאֱמַר, לְפִי שֶׁהוּא אוֹמֵר "לֹא תַעֲשֶׂה כָּל מְלָאכָה", אֵין לִי אֶלָּא דְּבָרִים שֶׁהֵן אָבוֹת מְלָאכוֹת, דְּבָרִים שֶׁהֵם מִשּׁוּם שְׁבוּת, מִנָּיִן, תַּלְמוּד לוֹמַר וּבְכֹל אֲשֶׁר אָמַרְתִּי אֲלֵיכֶם תִּשָּׁמֵרוּ, לְהָבִיא דְּבָרִים שֶׁהֵן מִשּׁוּם שְׁבוּת.