1,139. The Four Cups

Chometz u’Matzah 7:9

[In former times, wine was a strong concentrate that needed to be watered down to be palatable.] The four cups of wine should be diluted with water in order to make drinking them pleasant, according to concentration of the wine and the tastes of the one drinking. The four cups should collectively contain at least a reviis (about 3.3 ounces) of wine pre-dilution. If a person drinks four cups of undiluted wine, he has fulfilled his obligation to drink four cups of wine but he has not fulfilled the obligation to drink wine in the manner of free people. If a person drinks four cups of diluted wine all at once, he has fulfilled the obligation to drink wine in the manner of free people but he has not fulfilled the obligation to drink four cups. If one drinks the majority of each of the four cups, he has fulfilled his obligation.

Chometz u’Matzah 7:10

On each of the four cups, one recites the bracha of hagafen (that God created the fruit of the vine), plus the following. On the first cup, one recites kiddush. On the second cup, one recites the Haggadah. On the third cup, one recites bentching (grace after meals). On the fourth cup, one finishes Hallel and recites the blessing that follows songs of praise. One may drink in between cups if he so desires except for in between the third and the fourth cups.