Siman 488

In the morning they enter the beit knesset, and recite the zimirot as on Shabbat. And in "Mizmor Shir L'Yom HaShabbat" there are those who begin from "Tov L'hodot," for behold, today is not Shabbat. Nevertheless, there is no concern in this, for even Yom Tov is called "Shabbat," as regarding Yom Tov it is also written "Shabbaton." And such is the custom to begin as on Shabbat. And they pray the shacharit prayer, and complete the Hallel. Nevertheless, they do not recite the blessing "to complete the Hallel" but rather "to read," for perhaps he will skip one word and it will be a blessing in vain. And in a case of doubt whether he read Hallel or not—he does not return due to the doubt, for Hallel is d'rabbanan, and a doubt regarding a d'rabbanan is ruled leniently (Sha'arei Teshuva in the name of the Sha'agat Aryeh).

And one does not interrupt during Hallel except in the manner they stated regarding the recitation of Shema: that in the middle of a section, he may inquire after the welfare of his father or his teacher whom he must fear, and he may return a greeting to an honored person who greeted him. And between sections, he may inquire after the welfare of an honored person, and return a greeting to any person. And this is during the first two days when we complete the Hallel. But on the remaining days—their law is like Rosh Chodesh, and it was explained in siman 422. And if he paused in the middle, and delayed even long enough to complete all of it—he does not return to the beginning but rather to the place where he paused. And this law was explained above in siman 65, see there. And know that regarding Hallel, one who is proficient fulfills the obligation for one who is not proficient who hears it from him, and he has fulfilled his obligation. And it is possible for even ten people to be reciting, and he hears and fulfills his obligation. For even though regarding the Sefer Torah we say "two voices are not heard," nevertheless regarding Hallel, because it is beloved—he applies his mind and hears (Gemara Megillah 21a).

And after Shacharit, they take out two scrolls. And they read in one five men in the parashah of "Draw out..." until "from the land of Egypt by their hosts." And they do not add to the number of those called. And even though according to the core law it is permitted to add, as I wrote in siman 282, nevertheless it is not our custom to add, according to the opinion of the "there are those who say" brought there by our teacher, the Rema, see there. And when he finishes, he takes the second sefer Torah and places it on the table, and says Kaddish over both of them. And he calls the Maftir in the second, in the Musafim of "Pinchas." And the Haftarah is "The Pesach at Gilgal" in Joshua. And they pray Musaf. And the congregation mentions the rain, because it is not fitting to announce that they should not say rain, as on Shemini Atzeret when they announce that they should say rain. For rain is a blessing, and it is not appropriate to announce not to say it, and therefore they say it. And the shaliach tzibbur ceases from saying it in the prayer of Tal, and from then on the congregation also no longer mentions rain in Mincha. And the laws of rain were explained in siman 114. And they also cease from saying "Tal u-matar" during Chol HaMoed. And it is the custom to say on every Yom Tov the verses of Musaf in the Musaf prayer, after saying "from the mouth of Your glory, as it is said." And if he did not say it—he does not return.