Most Ashkenazim have the custom to fill both a fourth and a fifth cup at this point. This relates to a Talmudic discussion that concerns the number of cups that are supposed to be drunk. Given that the four cups are in reference to the four expressions of redemption in Exodus 6:6–7, some rabbis felt that it was important to include a fifth cup for the fifth expression of redemption in Exodus 6:8. All agreed that five cups should be poured but the question as to whether or not the fifth should be drunk, given that the fifth expression of redemption concerned being brought into the Land of Israel, which – by this stage – was no longer possessed of an autonomous Jewish community, remained insoluble. The rabbis determined that the matter should be left until Elijah (in reference to the notion that Elijah's arrival would precipitate the coming of the Moshiach (Jewish Messiah), at which time all halakhic questions will be resolved) and the fifth cup came to be known as the Kos shel Eliyahu ("Cup of Elijah"). Over time, people came to relate this cup to the notion that Elijah will visit each Jewish home on Seder night as a foreshadowing of his future arrival at the end of the days, when he will come to announce the coming of the Moshiach, and that the door is opened for him to enter.
Most Ashkenazim have the custom to fill both a fourth and a fifth cup at this point. This relates to a Talmudic discussion that concerns the number of cups that are supposed to be drunk. Given that the four cups are in reference to the four expressions of redemption in Exodus 6:6–7, some rabbis felt that it was important to include a fifth cup for the fifth expression of redemption in Exodus 6:8. All agreed that five cups should be poured but the question as to whether or not the fifth should be drunk, given that the fifth expression of redemption concerned being brought into the Land of Israel, which – by this stage – was no longer possessed of an autonomous Jewish community, remained insoluble. The rabbis determined that the matter should be left until Elijah (in reference to the notion that Elijah's arrival would precipitate the coming of the Moshiach (Jewish Messiah), at which time all halakhic questions will be resolved) and the fifth cup came to be known as the Kos shel Eliyahu ("Cup of Elijah"). Over time, people came to relate this cup to the notion that Elijah will visit each Jewish home on Seder night as a foreshadowing of his future arrival at the end of the days when he will come to announce the coming of the Moshiach, and that the door is opened for him to enter.