The Rambam in Hilchos Shabbos (29:1) writes, “It is a mitzvas asei min haTorah to be mekadeish the Shabbos with words, as the posuk says, “Zachor es yom haShabbos lekadsho.”
The Rambam adds, “It is required to remember Shabbos as it comes in with Kiddush, and so too when it leaves with Havdalah.”
In Halacha 18, the Rambam writes, “The same way we are mekadeish Shabbos on Friday night and we make Havdalah on Motzoei Shabbos, so are we mekadeish on Yom Tov night and we make Havdalah at the conclusion of Yom Tov. Why? Since they are all called Shabbos (Shabbsos hashem hein).”
The Minchas Chinuch (mitzvah 31) says that it would seem from here that Kiddush on Yom Tov is mide’Oraisa, since the Rambam writes that Yom Tov is called Shabbos and the Torah states, “Zachor es yom haShabbos lekadsho.”
However, the Maggid Mishnah on this Rambam says that Kiddush of Yom Tov is only miderabbonon.
The Acharonim question: Where did the Maggid Mishnah see this in the Rambam?
The Markeves Hamishnah explains that the Rambam in his introduction to Hilchos Shabbos mentions all the mitzvos going to be discussed, and one of them is to be mekadeish the Shabbos with zechirah. In Hilchos Yom Tov, when mentioning the mitzvos, he does not cite the mitzvah of Kiddush. We can infer from here that the Rambam holds that Kiddush on Yom Tov is miderabbonon.
The Magein Avrohom (Orach Chaim 271) paskens like the Maggid Mishnah that Kiddush on Yom Tov is only a rabbinical obligation. Rav Akiva Eiger says to refer to the Pri Megadim (296). The Pri Migadim cites a Shitah Mekubetzes in the name of the Ritva. The Gemara in Beitzah (4b) tells us that Rav Assi made Havdalah between the first and second days of Yom Tov. Asks the Ritvah, how was he able to make Havdalah if we have a sofeik whether Yom Tov is one long day or two days and sofeik derabbonon lekulah?
He answers that the obligation of Havdalah is a chiyuv min haTorah, and therefore it is a sofeik min haTorah which goes lechumrah, and thus Havdalah is indeed appropriate.
The Pri Megadim adds that if Havdalah is min haTorah, then Kiddush is min haTorah as well. We see from here that Kiddush on Yom Tov is a chiyuv min haTorah. The Pri Megadim concludes by saying that “this is a wonder.”
The Chasam Sofer (271) gives a reasoning for the term “wonder” as follows: How come the Magein Avrohom paskened that Kiddush is miderabbonon based on the Maggid Mishnah? Why did he not follow the Ritvah’s understanding that Kiddush of Yom tov is mide’Oraisa?
The Sefas Emes, in a letter to his son, the Imrei Emes, writes that everyone agrees that Kiddush on Pesach night is min haTorah. He bases it on the Gemara (Pesachim 117b) which states that “Rav Acha Bar Yaakov says that it is required to mention Yetzias Mitzrayim during Kiddush, as it says over here ‘lemaan tizkor es yom’ and it says over there ‘zachor es yom haShabbos lekadsho.’”
The Rishonim tell us that the Gemara is speaking about Kiddush of every Shabbos and is teaching us a halacha that it is required to mention Yetzias Mitzrayim. But why is this mentioned in the Gemara of Arvei Pesachim, which discusses inyonim of Pesach and not of Shabbos? He derives that the Gemara is coming to teach us regarding Kiddush the night of Pesach that it is required to mention Yetzias Mitzrayim.
We learn from “zachor es yom haShabbos lekadsho” that just as we need to mention Shabbos during Kiddush on Friday night, so too, on Pesach, during Kiddush, we need to mention Yetzias Mitzrayim, as it says “lemaan tizkor” (Michtevei Torah, siman 154).
It seems that Kiddush the night of Pesach is min haTorah, which is gleaned from a gezeirah shava from the Kiddush of Shabbos.
This same chiddush was also taught by the Torah Temimah, who brings a strong proof to back him. The Gemara says, “It is written over here ‘lemaan tizkor’ and is written over there ‘zachor es yom haShabbos lekadsho.’ If we are discussing Kiddush on Shabbos like the Rishonim understood, then it would be appropriate to say Shabbos here and Yetzias Mitzrayim over there. The fact that the Gemara says lemaan tizkor, which is stated in the pesukim regarding Pesach, it is proof that we are discussing Kiddush of Pesach. (Rabbeinu Chananel, though, has a girsa of zachor here and lemaan tizkor there.)
The Gemara (Brachos 20b) teaches us that women are mechuyav in Kiddush on Shabbos, since whoever is included in the mitzvah of shamor is also responsible for zachor. Yet, Rav Akiva Eiger notes that women are not obligated to make Kiddush on Yom Tov (Hashmata 271).
Similarly, the Pri Megadim in Tevas Goma (Parshas Nitzavim) says that since Kiddush on Yom Tov is only a chiyuv miderabbonon, noshim are exempt.
Furthermore, the Minchas Chinuch (mitzvah 31) explains that if Kiddush on Yom Tov is min haTorah, then noshim are obligated in Kiddush on Yom Tov, because zachor is referring to Yom Tov as well. However, if the chiyuv on Yom Tov is miderabbonon, then noshim are not obligated in Kiddush on Yom Tov.
However, the Shulchan Aruch Harav (271:5) holds that women are obligated in Kiddush on Shabbos min haTorah and on Yom Tov miderabbonon, since whoever is included in shamor is included in zachor as well.
The explanation to the Shulchan Aruch Harav is in accordance with the view of Rav Moshe Feinstein zt”l (Igros Moshe, Orach Chaim 4, siman 100), who paskens that noshim are obligated in Kiddush on Yom Tov, since the Rambam says that all Yomim Tovim are called Shabbos, and therefore we can apply the rule that whoever has shamor is required in zachor too.
Rav Moshe adds that the Gemara in Pesachim (108) says that noshim are obligated in the four kosos at the Seder. We know that the first cup is Kiddush and it is not logical that they should only be mechuyav in Kiddush on Pesach and not all year.
Interestingly, the Raavya in Brachos (siman 61) paskens that noshim are obligated in Kiddush on Yom Tov min haTorah.
Additionally, the Kiryas Sefer (Hilchos Avodah Zarah, Perek 12, halacha 3) explains that the Rambam who says that noshim are obligated min haTorah in Kiddush on Shabbos maintains that the same chiyuv de’Oraysa will apply to Kiddush on Yom Tov.
Furthermore, the Kesef Mishnah (Hilchos Brachos 11:10) brings the shitah of the Ramach that women are obligated in Kiddush on Yom Tov min haTorah, and he himself concurs with this shitah. Similarly, the p’sak of the Yeshuas Yaakov (siman 417) and Shu”t Toras Refoel (siman 21) is that woman are mechuyav in Kiddush on Yom Tov mide’Oraysa.
The Behag brings a posuk for the source of Kiddush on Yom Tov. The Netziv in Haamek Shailah explains that the existence of the posuk as a mekor indicates that Kiddush is indeed min haTorah. However, the Eliyahu Rabbah explains that the posuk is merely an asmachta, and the Behag maintains that the chiyuv of Kiddush on Yom Tov for noshim is only midrabonon.