In accord with the Ten Commandments, a part of the Torah, Jewish people celebrate a Shabbat, a day of rest on the seventh day of the week. Jewish law defines one day ending at nightfall, which is when the next day then begins. Thus, Shabbat begins at sundown Friday night, and ends at sundown Saturday night.
The Tanach (Hebrew Bible) and the Siddur (Jewish prayer book) describes Shabbat as having two purposes: It is a commemoration of the Israelites' redemption from slavery in Egypt, and also is a commemoration of God's creations of the universe; on the seventh day God rested from his work.
Halakha strictly prohibits Jewish people from doing any form of melachah (work) on Shabbat. However, note that the term melacha does not closely correspond to the English definition of the term work, nor does it correspond to the physics definition of the term. Melachah refers to the 39 categories of activity that the Talmud prohibits Jews from engaging in on their Sabbath. Many religious scholars have pointed out that all these labors have something in common - they prohibit any activity that is creative, or that exercises control or dominion over one's environment.
The 39 activities prohibited by Jewish law on Shabbat are as follows: Sowing, Sowing, Plowing, Reaping, Binding sheaves, Threshing, Winnowing, Selecting, Grinding, Sifting, Kneading, Baking, Shearing wool, Washing wool, Beating wool, Dyeing wool, Spinning, Weaving , Making two loops, Weaving two threads, Separating two threads, Tying, Untying, Sewing stitches, Tearing, Trapping, Slaughtering, Flaying, Salting meat, Curing hide, Scraping hide, Cutting hide up, Writing two or more letters, Erasing two or more letters, Building, Tearing something down, Extinguishing a fire, Kindling a fire, Hitting an object with a hammer, and taking an object from the private domain to the public, or transporting an object in the public domain.
Link: [Frequently Asked Questions about Shabbat]
Link: [Information on Shabbat from the Union of Orthodox Congregations]
Link: [Discussion of Shabbat Torah readings]
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