Siman 481

There was a tradition in the hands of the Geonim that if one wishes to drink a fifth cup—he may drink. The Rambam wrote similarly in the eighth chapter, and this is his wording: And afterwards he pours a fourth cup, and completes the Hallel over it, and recites over it the blessing of the song, which is "All Your works shall praise You, Hashem...". And he recites the blessing "Who creates the fruit of the vine," and he does not taste anything afterwards for that entire night except for water. And he may pour a fifth cup and recite over it the Great Hallel, from "Give thanks to Hashem for He is good" until "By the rivers of Babylon." And this cup is not an obligation like the four cups. Thus far his words. And such was their version in the Gemara (118a): On the fifth—he recites the Great Hallel. But in our version it was emended according to the commentary of Rashi and the Rashbam: On the fourth, see there. And the Tur elaborated on this. And there are those who said that on the fourth cup he concludes with the blessing of "Yehalelukha," and on the blessing of the Great Hallel he concludes with the blessing of "Yishtabach." And there are those who said that he drinks the fourth without a concluding blessing, see there. And in the Hagahot Maimoni: However, we do not know of this, and we know only of four cups.

And there are some of the Geonim who said that this is specifically in a case where he is compelled to a fifth cup, such as if he is longing to drink, as our teacher Yosef Tuv Elem established in the piyut "Elohei HaRuchot" for Shabbat HaGadol, see there. And this is what our teacher, the Rema, wrote, that one who is an istanis or longs greatly to drink – may drink a fifth cup, and recite over it Hallel HaGadol. Thus far his words. However, in our days we have not heard nor have we seen people practicing so.

And that which the Rambam wrote, that it is forbidden afterward to drink wine but only water—so too wrote the Rif. And the Rosh raised a difficulty, for behold we learned in a Mishnah: "One may not conclude after the Pesach with an afikoman"—but to drink is permitted, see there—however, the custom of the entire world is like the Geonim. And Rabbeinu Yonah explained the reason because a person is obligated to occupy himself all night with the Exodus from Egypt, and to tell of the miracles and wonders that the Holy One, Blessed be He, performed for us until sleep overcomes him. Therefore, if he drinks more wine—sleep will overcome him immediately. And there are those who wrote [the reason is] so as not to nullify the taste of the matzah in his mouth, and all liquids are forbidden except for water. And licorice water, and ginger water which is called ingber wasser—is permitted (Magen Avraham). And so too with us, seltzer and lemonade—is permitted, as I wrote in siman 478. But apple drink in Ashkenaz, where they crush apples in a press and they have a strong taste—is forbidden (ibid.).

Every law of the first night applies as well to the second night. And even regarding the matter of not tasting anything after the seder, the meticulous also follow the custom as on the first night (Beit Yosef). And it is the custom not to recite upon one's bed on these two nights anything other than the section of "Shema" and the blessing of "Hamapil," and not the other psalms that are always customarily recited for protection, for the night of Pesach is a night of guarding against the damaging spirits.