Did you ever wonder why on a holiday the Kiddush made over wine ends with the words; מקדש ישראל והזמנים, “Hashem sanctifies Israel and the festivals”? On Shabbat we do not mention Israel but merely mention: מקדש השבת, “He sanctifies the Shabbat”. Why is Israel left out on Shabbat?
We read in this week’s Portion that the Shabbat was just given to Israel after the Exodus as a commandment to obey. רְאוּ כִּי יְקֹוָק נָתַן לָכֶם הַשַּׁבָּת, “See that Hashem has given you the Shabbat…”. (Ex.16,29) The Mitzvah of Shabbat was given even before the Torah was given. But notice it does not say that the Shabbat was sanctified at this time.
Shabbat was sanctified by Hashem during the days of Creation. There we read: וַיְבָרֶךְ אֱלֹקִים אֶת יוֹם הַשְּׁבִיעִי וַיְקַדֵּשׁ אֹתוֹ, “Hashem blessed the seventh day and sanctified it.” (Gen.2,3) Hence we see that the sanctification of Shabbat did not depend on Israel. Hashem had sanctified it during Creation.
The Jewish holidays, on the other hand, depend of the proclamation of the Jewish Bet Din, the court that sets the day of the New Moon, and thus the days when the holidays occur. Therefore it is really the Jewish people who sanctify the holidays, hence we recite during Kiddush, that Hashem sanctifies Israel who in turn sanctifies the holidays.