Question: How come Kiddush for Shabbat contains different phrases regarding the Jewish people’s chosenness than Kiddush for Yom Tov? In Kiddush for Shabbat it states, “Ki vanu vacharta… – For you choose us and sanctified us from all the nations.” In the Kiddush for Yom Tov, though, it states, “Asher bachar banu mekol am… – Who has chosen us from among all the nations, exalted us above every tongue, and sanctified us with His commandments.” Why the different expressions?
Answer: The Beit Yosef explains that Shabbat was given to the Jews in Mara and thus predated their selection as the chosen people at Mount Sinai (Orach Chayim 271).
But this still doesn’t answer the question since Kiddush for Shabbat does contain a reference to the concept of chosenness.
HaRav HaGaon R. Natan HaLevi Bamberger, av beit din of Wurzberg, resolved the issue as follows. He explained that the selection of Klal Yisrael as the chosen people occurred in the time of Avraham. It is to this selection that the Kiddush of Shabbat refers. On Yom Tov, however, quite a different type of selection is described. The Yom Tov Kiddush concerns the fact that Hashem sanctified us with mitzvot – “asher kidshanu b’mitzvotav.”
We were only chosen to perform the mitzvot at Mount Sinai. That’s why the Shabbat Kiddush does not refer to this aspect of chosenness. (The halachic notes of HaRav Natan Bamberger are located in a volume titled Kitvai Rabbainu Yitzchok HaLevi Mi’Vertzberg, pp. 197, 198.)