Siman 663

On Chol HaMoed, one prays Arvit, Shacharit, and Mincha as on a weekday, and mentions "Ya'aleh V'Yavo" in the "Avodah" blessing. And if he did not say it—he is returned. And one recites the blessing every day over the lulav, and completes the Hallel. And it is not similar to Pesach, where one does not complete it, for Sukkot—each day is a festival in its own right, as their sacrifices are distinct. And one reads from the Torah regarding the matter of the day, as will be explained, and one prays the Musaf of Yom Tov. And one says Hoshanot as they are printed in the prayer books, and others from what is said on Hoshana Rabbah, such as "A'aroch Shui," "El L'mosha'ot." But there are those who say from the order of Hoshana Rabbah in sequence, and ostensibly, why should we change? However, one does not refute the custom in a matter where according to the law there is no hindrance, whether thus or thus.

And since the reading on Chol HaMoed—it is only possible during these six days, from the second day until after the seventh day, such that on each one—it is only possible to read one reading, and every day there are four olim, for on Chol HaMoed we read four—and if so, it is necessary that the second shall read what the first read. And there are differing customs regarding this. Our teacher, the Beit Yosef, wrote that on the first day the Kohen reads "And on the second day," and the Levi "And on the third day," and the third and the fourth return and read this, meaning: the third shall read "And on the second day." However, the fourth shall read both of them: "And on the second day"-"And on the third day," because of the doubt of the day, so that one shall read the two doubts. And on the second day of Yom Tov he does not read "And on the second day," so as not to treat the second day of Yom Tov lightly, so as not to show that there is a concern of it being a weekday. And in this manner they read on all the days.

But our custom is according to our teacher, the Rema: that the first calls "And on the second day," Levi "And on the third day," the third "And on the fourth day." And the fourth calls the doubts: "And on the second day"-"And on the third day," and so too every day. And only on Hoshana Rabbah will the Kohen need to begin from "And on the fifth day," Levi "[And] on the sixth day," the third "And on the seventh day," and the fourth "[And] on the sixth day"-"And on the seventh day," for it is impossible in any other way, obviously. And such is the simple custom among us. And this is all in the diaspora. But in the Land of Israel, where there is no doubt of the day – all those called to the Torah read the current day. For example: on the second day – everyone reads "And on the second day," and on the third – "And on the third day," and so too all of them in this manner.

On the Shabbat of Chol HaMoed, for Arvit, Shacharit, and Mincha – one prays the prayer of Shabbat. And one says "Ya'aleh Veyavo" in the "Avodah" blessing. And if one did not say it – they return him. And in Musaf one prays the prayer of Yom Tov, and includes that of Shabbat, and concludes "Who sanctifies the Shabbat, Israel, and the seasons." And they say "Adir Adireinu" in the Kedushah, and they say Hoshanot. And they say "Kohelet" after Shacharit. And if Shemini Atzeret falls on Shabbat, they say it on Shemini Atzeret, and without a blessing. And they take out two scrolls. In one he reads "See, You say...", and the Maftir is in the doubt of the day. And the Haftarah is in Ezekiel, regarding Gog and Magog, which will take place during the festival of Sukkot. And he concludes in the Haftarah: "Who sanctifies the Shabbat, Israel, and the seasons."