Halakhah for Berakhot 103:3

The commandment of the sanctification of Shabbat with words: To speak words on the Shabbat upon its entry and also its departure - that there be in them cognizance of the greatness of the day and its stature and its positive distinction from the other days before it and after it; as it is stated (Exodus 20:8), "Remember the Shabbat day, to sanctify it," meaning to say, remember it with a memory of [its] holiness and greatness. And in explanation, our Sages told us (Pesachim 110a) that we are commanded to say these things upon wine - as so does the explanation come: remember it over wine. And the content is that we place into a cup a reviit or more of pure or mixed wine - but not less than this (Pesachim 108b). And it is known that the [proportions of the] mixture is one part pure good wine to three parts water. And we recite the blessing of the Kiddush (sanctification) of Shabbat upon it, according to the wording that is known among the Jews. And so [too], at the departure of Shabbat, we recite the blessing over the wine in honor of the day - and that blessing of the conclusion of Shabbat is called Havdalah (Berakhot 52a).