The total number of categories of labor performed in the construction of the Tabernacle is thirty-nine. In halakhic literature these are commonly referred to as the thirty-nine primary categories [avot] of labor. They are called avot, literally fathers, because they also have toladot, “descendants” or subcategories, which are actions that are similar to the avot. These too are prohibited by Torah law, just like the primary categories.

These are the thirty-nine primary categories of labor:

1. Plowing: All actions performed on the earth to improve, straighten, or soften it, or in order to benefit the growth of crops, are included in the labor of plowing. This includes deliberately making a groove in the ground.

2. Sowing: Laying seeds in the ground so that they will grow. This prohibition also includes all actions that lead to the cultivation and strengthening of existing plants, such as irrigation.

3. Reaping: Detaching a plant from the source of its growth. Plucking leaves from trees, cutting grass, and the like are all included in this labor.

4. Gathering: Collecting and accumulating crops into piles within their area of ​​growth.

5. Threshing: Detaching and separating crops from their shell or from the waste that grows together with them, such as separating grain from sheaves and chaff. This labor also includes squeezing out certain liquids from solids, most prominently squeezing fruit that is generally squeezed in order to make juice.

6. Winnowing: Separating waste from food by the aid of the wind.

7. Selecting: Separating food and waste that are mixed together. For the purposes of this labor, “waste” is not necessarily an absolutely unwanted substance; the prohibition also applies to the separation of two types of food from one another, if one of them is unwanted by the person at that time.

8. Grinding: Reducing a crop into small parts, e.g., grinding grains or spices.

9. Sifting: Separating waste from food by means of a perforated vessel, such as sifting flour with a sieve.

10. Kneading: Causing small items to adhere to each other by means of liquid, thus forming a uniform solid. The most prominent example of this is kneading dough. Even the preparation of porridge or oatmeal in the usual manner is prohibited due to the labor of kneading.

11. Baking: Preparing substances for eating, through the heat of a fire. This prohibition includes baking, cooking, and frying.

12. Shearing: Disconnecting an item from the place of its natural growth on the human body or the body of animals. This labor includes cutting one’s hair or nails.

13. Whitening: An action that cleans or even merely adds a shine to objects that are typically laundered.

14. Combing: Preparing raw materials that will be made into yarn or thread.

15. Dyeing: An action aimed at permanently changing the color of an object.

16. Spinning: Making threads from raw material, in any manner.

17. Stretching: Stretching the threads of the warp in the loom as a prelude to the act of weaving.

18. Constructing two meshes: Inserting two threads of the warp through the heddle rings. This refers to sticks with holes through which one inserts the threads of the warp before weaving, each thread into a different mesh.

19. Weaving: Passing threads of the woof through the threads of the warp.

20. Severing: Completing the work of weaving a garment by removing the remaining threads.

21. Tying: Tying a permanent knot.

22. Untying: Untying a permanent knot.

23. Sewing: Attaching two items to each other. Even gluing together two pieces of paper is included in this labor.

24. Tearing: Tearing something for a particular purpose, such as to repair or sew it.

25. Trapping: Capturing animals that are typically hunted, whether to eat them or to use them for any other purpose. It should be noted that potentially harmful animals, such as snakes, may be trapped and even killed on Shabbat.

26. Slaughtering: Killing an animal in order to use it. This labor also includes the prohibition against bruising another person.

27. Flaying: Stripping the hide from the flesh of animals.

28. Tanning: Processing raw materials to prepare them for use. An example of this labor is pickling cucumbers.

29. Smoothing: Smoothing animal skins as part of their preparation for use. This labor includes polishing shoes with a thick shoe polish.

30. Etching: Etching or drawing a line on an object in order to cut it evenly.

31. Cutting: Cutting something in a precise manner and according to a particular measure.

32. Writing: Writing letters, or other shapes that have meaning.

33. Erasing: Erasing an enduring writing in order to write at least two other letters in their place.

34. Building: An action that assists in the construction of buildings or parts of them. While this labor refers mainly to building items that are connected to the ground, construction of furniture or utensils in a professional manner is also included in this prohibition.

35. Demolishing: Dismantling all or part of an item in order to repair it, or in preparation for alternative construction.

36. Kindling: Lighting a fire, as well as increasing or extending the duration of a fire.

37. Extinguishing: Putting out or reducing a fire, e.g., extinguishing coals in order to make charcoal.

38. Striking a blow with a hammer: Applying the finishing touches to an item.

39. Carrying from one domain to another: Transferring an object from a private domain to a public domain or vice versa.

Further reading: The directive to observe Shabbat appears in many places in the Torah, see A Concise Guide to the Torah: pp. 174, 183, 192, 217, 224, 302, 315, 449.

Besides the thirty-nine primary categories of labor and their subcategories, which are all prohibited by Torah law, the Sages added additional prohibitions. These rabbinic decrees form a category known as shevut, a term derived from the verse, “And on the seventh day you shall rest [tishbot]” (Exodus 34:21).

The shevut prohibitions include actions prohibited by the Sages for one of the following reasons: It is similar to one of the thirty-nine labors, e.g., collecting honey from a beehive, which is like the labor of reaping; it may lead to the performance of a labor that is prohibited by the Torah, e.g., smelling fruit that is attached to the tree, as one might detach the fruit; and actions that spoil the atmosphere of rest and the sanctity of Shabbat, such as talking about matters of work and business.

The category of shevut also includes the prohibition against instructing or asking a gentile to perform a labor on behalf of a Jew that the Jew is not allowed to do himself. Nevertheless, this is permitted under certain circumstances, subject to several halakhic qualifications (see p. 456).

Further reading: Why must we refrain from labor on Shabbat? See A Concise Guide to Mahshava, p. 35ff.