Chapter 119:2
Laws of the Seder
2. One's servant or another member of the household should pour the wine
into the cups. Similarly, each time the cups are filled, they should be
filled by these individuals and not by the person leading the Seder
himself; this is an outward expression of freedom (1).
One should instruct the members of one's household to drink the majority of
the cup in one gulp, and to drink at least a revi'is (2) for the fourth cup
(3). They must also have the intent to fulfill [four different] mitzvos:
the drinking of the four cups of wine, the relating of the story of the
exodus from Egypt (4), and eating matzoh and marror. Women are also
obligated to fulfill these mitzvos, but it is not customary for them to
recline.
One should recite Kiddush as it is printed in the Haggodos and drink the
cup while reclining on the left side.
If possible, it is proper to follow the opinion of the authorities who
require that one drink the entire cup of wine for each of the four cups
(See note 2).
FOOTNOTES:
(1) Royalty and nobility never pour their own cup of wine. Each person at
the table who is performing the mitzvah of drinking four cups, should have
someone else pour the wine each time.
(2) A "revi'is" literally means "one quarter" because it is equal to the
volume of one quarter of a "log." There is a dispute among the authorities
as to what a revi'is equals in modern measurements. The opinions range from
88.7 ml to 150 ml (5.07 fluid ounces).
If the cup is capable of containing only a revi'is, one should preferably
drink the entire cup of wine for each of the four cups. However, if one is
unable to complete the cup, one can fulfill one's mitzvah by drinking most
of the revi'is, a measure referred to as "maleh lugmav," which literally
means a "cheek-full" (a quantity of liquid which fills one cheek of an
average person).
If the cup is capable of holding more than a revi'is, the Ramban rules that
one must drink most of the contents of the cup, whereas the Ran rules that
it is sufficient to drink most of a revi'is. One should preferably conduct
oneself in accordance with the Ramban, however, if one only drank most of a
revi'is of a large cup (containing more than a revi'is), one has fulfilled
his obligation ("Halachos of Pesach," by Rav Shimon Eider Vol II, pg 230
(Ch20 E1))
The preferred manner of drinking the revi'is is by drinking most of the
revi'is in one gulp, and completing the revi'is in the second gulp. If it
takes him more than nine minutes to drink the revi'is, he must drink the
cup again, with a new blessing, in order to fulfill the mitzvah ("Halachos
of Pesach," by Rav Shimon Eider Vol II, pg 233 Ch20E3).
One should make sure to drink an entire revi'is for the fourth cup, because
the "bracha acharona" ("after-blessing"), recited after the fourth cup, may
only be recited after drinking a revi'is.
(3) Even if drinking four cups of wine will cause someone slight
discomfort, such as a mild headache, one is still obligated to do so. One
may dilute the wine with grape juice or water (preferably grape juice), but
one should try to do it in a way that the alcoholic taste of the wine
remains. Also, when diluting with water, one must be careful to use the
ratio required to retain the blessing of "Borei Pri HaGofen" (more than one
part wine to six parts water; the fact that some modern wines are already
diluted must be taken into account).
One is not obligated to do anything that will cause him to become
bedridden. Therefore, if one is unable to drink any wine (or can only drink
a small amount), one may fulfill the mitzvah of the four cups using just
grape juice. If one is allergic to grape juice, one may fulfill the
obligation by drinking four cups of "Chamar Medina" ("beverage of the
country"), which is generally defined as a drink one would serve to a guest
even when he is not thirsty, such as alcoholic beverages (make sure they
are not chometz), tea, and coffee ("Halachos of Pesach" by Rabbi Shimon
Eider, Vol II, pg 220-225; for further details, ask your local orthodox rabbi).
(4) Relating the story of the exodus on the night of Pesach is a Biblical
commandment.