Sanctifying the Shabbat

"Remember the Shabbat to keep it holy"Exodus 20:8.

We are commanded to honor the Shabbat when it enters and when it leaves by pronouncing words that proclaim the greatness and holiness of the day, and its distinctness from the weekdays that precede and follow it. This mitzvah – commonly known as kiddush and havdalah – is performed over a cup of wine.