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29. Koshair: Knot What You Think

July 21, 2015 | by

A halachic knot is permanent and tight.

As I was preparing this lesson, I came across a curious event listed in a national magazine. It was a knot-tying demonstration, and the description read, in part: "Knots... have been vital throughout history to the livelihood of farmers, cattle hands, sailors, and [others]."1 In fact, there are hundreds of types of knots, many devised specifically for a particular usage.

Knots were needed in the Tabernacle, to tie together stitches at the end of a piece of fabric.2 Therefore, it is the next logical labor category in the sequence we are now studying.

What is a Knot?

As we'll explain, not everything that we call a "knot" is actually a knot according to halacha (hence our lesson's title).

There are two major characteristics of a knot in halacha:

  • it is permanent3
  • it is tight and therefore unlikely to come undone4

By "permanent," we mean a knot that is intended to last for at least 24 hours. (In halacha, the prohibition is greater if the knot is intended to remain tied for more than one week, and even more so if the intent is for one month.)5 An example might be a thread of tzitzit (ritual fringes) or a knot used to tie a boat to a dock.

By "tight" and "unlikely to come undone," we mean that the knot is tied in a way that it is strong and will hold (barring some unusual event). The conventional double knot is a classic example.6

Of course, you can have a knot that is "permanent" but not "tight": for instance, the docked boat may be attached by a rope that is meant to be there for weeks or months, but it could actually be pretty loose.

Similarly, there can be a knot which is "tight" but not "permanent": the typical shoelace knot, although very strong, is not meant to be left tied for very long. Most people untie their shoes at the end of the day, when they remove them.

For something to be a knot according to Torah law, both conditions need to be met: that is, it needs to be both "permanent" and "tight." If it has only one of these characteristics, it qualifies as a knot according to rabbinic law.7

Defining an Act of Koshair

Tying either a Torah-level knot or a rabbinic-level knot is an act of Koshair, and therefore can't be done on Shabbat.

The flip side of this rule is that any knot which is neither "permanent" nor "tight" may be tied on Shabbat. The most common example is the garden-variety bow knot used to tie shoes. It is not "tight" according to our definition, since it can come undone relatively easily; and it is not "permanent," since it is intended to be untied at the end of the day.8

Now, let's say you are someone who ties your shoes, leaves them tied until the next time you wear them, and then just slips into them. You would not be able to tie your shoes on Shabbat. Why? Because for you, the knot is considered "permanent," since you do not loosen it within 24 hours.9

Some other examples of knots:

Neckties – Most opinions allow you to tie a necktie on Shabbat. This is because the way a tie is formed does not involve a true halachic knot. Instead, it involves a variation on a slip-knot, which is "a knot made so that it can readily be untied by pulling one free end."10

Because a slip-knot can be easily undone, it is viewed differently than a true knot. In Hebrew, the terminology is also different: a true knot is called a kesher, while a slip-knot is known as an anivah.11

Overhand Knot – Imagine taking a single string, and giving it a single knot on itself. This is prohibited, because it cannot be untied by pulling one end.12

Garbage bags – Many garbage bags have two small loops at the top, which are meant to be pulled up and tied to each other once the bag is full. Tying them in this way is similar to the bow-knot used for shoes, and is permissible.

Twist-ties – Also common in the kitchen, twist-ties (small threads of wire used as fasteners) may present a problem of Koshair. Therefore they should either be untied within 24 hours, or initially the ends should only be twisted around once.13

Loosely double-knotted belts – Many raincoats and bathrobes come with a belt that is meant to be tied loosely at the waist. Often, the belt will not stay on if you loop the ends together only once. You may make two loops to hold the belt in place on Shabbat, because (a) even when doubled, the knot is quite loose and (b) you are certain to undo it within 24 hours. This is an exception to the usual rule about double-knots.14

Koshair has a 'partner' labor category, which is known as Matir (Untying). We'll turn now to this issue.

Matir: Untying a Knot

This seems at first to be a strange melacha, since it is about undoing, rather than creating – and, as we learned at the very beginning of this course, the laws of Shabbat are about creative labor. Indeed, some authorities rule that Matir15 is only prohibited if you are untying the knot so as to retie it in a different, or better, way.16

According to other opinions, however, Matir stands on its own as a melacha based on a particular activity done in the Tabernacle. In order to obtain a certain blue dye, known as techeilet, the Jews needed to capture a sea-creature that produced this coloring. The trapping required nets, and constructing the nets involved both tying and untying strings. Therefore, the act of untying emerged as a separate labor category.17

Understanding the Melacha

Matir is essentially the mirror image of Koshair: All knots which are permitted to be tied on Shabbat are permitted to be untied, and all knots which are prohibited to be tied are prohibited to be untied.18

As a leniency of Matir, you are allowed to undo a knot that

  1. was meant to last for 24 hours or less

  2. or

  3. was meant to last for a week or less, but the knot is causing discomfort or hardship. For example, if a person has an item of clothing that has been double-knotted (say, a decorative part of a dress), and can't use it without undoing the knot, she may do so.19

Another leniency is that any accidentally-tied knot (whether tied on Shabbat or beforehand) may be untied on Shabbat, because it was never considered a "knot."20

You cannot undo a knot that was made to last for more than a week – anything above this time frame is considered to be "permanent" from a halachic perspective.21

Practical Cases

Matir comes into play in some common situations.22

The bakery cake – We all love to get nicely wrapped cakes from the kosher bakery. But often those thin strings used to tie the package are impossible to get off. If so, it is better not to untie it – because, if it's so difficult to undo, it qualifies as a "permanent" knot. There is a permitted alternative, however: You can use a scissors or knife to cut the string in the middle (thereby spoiling it), and not in the spot of the knot.23

Bagged food items – Some items come packaged in a sealed plastic bag with a knot at its end. It is better to rip the bag and remove the food, rather than untie the knot.24

Shoelaces – Just as we cannot tie laces in a double-knot, we can't undo such a knot, either – unless (as we noted earlier) it is causing discomfort (i.e. you can't get the shoe off otherwise).25

  1. 1 The New Yorker, November 20, 2006, p. 28.
  2. For additional reasons as to why knots were needed, see Talmud – Shabbat 74b; Jerusalem Talmud 7:2; Me’iri on Talmud – Shabbat 73a; 39 Melochos, p. 783.
  3. This is known in Hebrew as a kesher shel kayama (an ‘everlasting’ knot).
  4. The Hebrew term for this is kesher uman (a professional knot). On both of these concepts, see Biur Halacha 317:1; 39 Melochos, p. 784-86.
  5. Beit Yosef (Orach Chaim 317).
  6. Mishnah Berurah 317:14.
  7. Orach Chaim 317:1; Mishnah Berura Introduction to Koshair; 39 Melochos, p. 790 and 792.
  8. Rema – Orach Chaim 317:1; Shemirat Shabbat K’Hilchato 15:52; 39 Melochos, p. 791 and 796.
  9. Mishnah Berurah 317:29; Shemirat Shabbat K’Hilchato 15:53 and 39 Melochos, p. 798.
  10. Definition and image courtesy of (
  11. Anivah is, in fact, the modern Hebrew word for a necktie.
  12. Orach Chaim 317:1, Mishnah Berurah 15.
  13. For more details, see Addenda to Shemirat Shabbat K’Hilchato 15 (166); 39 Melochos, p. 799- 800.
  14. Sha’arei Teshuva 317:1; 39 Melochos, p. 797.
  15. Pronounced mah-TEER. This word is identical to the word for permitting an action in halacha. Both share the connotation of ”to free something up.”
  16. Tosfot Shabbos 73a s.v. ‘HaKoshair’; Biur Halacha 317:1 s.v. ‘Dino’; 39 Melochos, v.3, Hebrew section, p. 786, fn. 2.
  17. Rashi (Shabbat 74b s.v. Shari); Rambam (Shabbat 10:8); 39 Melochos, p. 805. The name of the dye is pronounced teh-KHAY-lett.
  18. Rambam (Shabbat 10:7).
  19. Rema – Orach Chaim 317:1; 39 Melochos, p. 806; see also Shemirat Shabbat K’Hilchato 15:55. In other words, this last type of knot could not be made on Shabbat, but under these limited circumstances, it can be undone.
  20. Chayei Adam (Shabbat 27:2).
  21. Orach Chaim 317:1.
  22. For these, see Orach Chaim 314:7-8; 39 Melochos, p. 807-08.
  23. Mishnah Berurah 317:7; Shemirat Shabbat K’Hilchato 15:54.
  24. Shemirat Shabbat K’Hilchato 9:14. As we’ll learn later, G-d willing, we need to be careful not to rip through any words on the packaging.
  25. Rema – Orach Chaim 317:1.
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