The greatest of all Jewish religious holidays is Shabbat Saturday. Science could not find any similar religious tradition in any nation or religion before genesis of this great holiday. Shabbat literally means abstention from any physical work of human activity. According to the later tradition, thirty-nine forbidden jobs during Shabbat were enlisted, what in practice means that any active work is prevented.
During the seventh day of the week the Creator himself took a rest from his six-day work on creation of the world. In his book (Bereshit 2,1-3) Moses wrote:
“…Thus the heavens and the earth were finished, and all the host of them.
And on the seventh day God ended his work which he had made; and he rested on the seventh day from all his work which he had made.
And God blessed the seventh day, and sanctified it: because that in it he had rested from all his work which God created and made…”
Shabbat lasts from sunset of the sixth day (Friday) until stars appear on the Saturday evening sky, the way Jews are counting beginning and end of all other days during week. A 24-hour celebration is ended with a special ritual on mocae Shabbat coming out of Saturday, when sacred things are separated from civil, secular.
E. Werber: Introduction to Jewish Religion