Derekh Hashem, Part Four, On Divine Service and the Calendar

Delighting in the Shabbat and honoring it: And besides that we are forbidden to violate the honor of the holiness that flows on this day - as we have written - we were also commanded [to] honor this holiness that flows. And that is the principle of the delighting (oneg) in the Shabbat, and honoring (kavod) it upon its entering and leaving, with Kiddush and Havdalah [respectively]. And the rest of all of its details are matters generally based upon this fundamental principal, which is to keep ourselves properly worthy for the holiness that flows upon us [on Shabbat]; and to cherish it, in honor of its content - which is great closeness to Him, may He be blessed, and great cleaving to Him - and to honor that He, may He be blessed, gave us such a big gift as this. And the details of [these] matters correspond to the details of this holiness, its characteristics, its ways and its effects, according to what they actually are.