Question:
Sometimes the top knot of my Tzitzis becomes loose, and during the week I usually tighten it. On Shabbos, I’ve noticed that people occasionally tighten it as well, sometimes even intentionally to ensure their Tzitzis remain kosher. Is it permitted to tighten the knot of Tzitzis on Shabbos? And if the knot becomes loose, does it invalidate the Tzitzis?
Answer:
It is absolutely forbidden to tighten the knot of Tzitzis on Shabbos, possibly as a biblical violation, and at the very least rabbinically prohibited. However, even if the knot becomes loose, the Tzitzis remain kosher and valid. [Special care is needed with a new pair of Tzitzis, where the upper knot commonly loosens; one must therefore be careful not to tighten it on Shabbos.]
Practically, because of the prohibition against tightening, when checking or separating Tzitzis on Shabbos, the customary practice is to hold the knot in place to avoid inadvertently tightening it. This precaution has been specifically demonstrated by the Rebbe.
Explanation:
One of the prohibited categories of labor on Shabbos is koshair (tying or fastening a knot). Tightening an existing knot can fall under this prohibition as well.
There is a well-known dispute among the Rishonim [between Rashi and Rambam] regarding what constitutes a biblically prohibited knot. According to Rambam, the key factor is whether the knot is intended to last permanently, irrelevant to whether the knot is professional or amateur. According to Rashi, an additional determining factor is whether the knot is considered professional or strong in nature.
The knot used in Tzitzis—particularly the upper knot—is typically a double knot and is intended to remain permanently. It is also considered a strong and professionally made knot. Therefore, tightening this knot would meet both criteria and would be prohibited according to all opinions.
That said, in practice, the top knot of Tzitzis often loosens over time. One could argue that since it does not reliably last, it may not meet the definition of a permanent knot according to the opinion that requires durability for a biblical prohibition. Nevertheless, even under this reasoning, tightening the knot would still be at least rabbinically prohibited and therefore may not be done on Shabbos. [Perhaps, however, if one does not tighten the knot down onto the lower knot but merely brings it somewhat closer while leaving it loose, this would not constitute any prohibition and so suggest some authorities. In my view, however, this too should be avoided, as it is a risky practice: even a light adjustment can easily lead to actual tightening.]
Regarding the validity of the Tzitzis: even if the top knot becomes loose to the point that it is no longer halachically considered a knot, the Tzitzis remain kosher. This is because the essential halachic requirement is fulfilled with a single structure of knots and windings which I a single braid covered by double knots. All the braids above the first braid with its double knot are a customary addition and not strictly required for validity. Therefore, even if the top knot loosens or is no longer functional as a knot, the Tzitzis are still valid according to all opinions.
Sources:
Ketzos Hashulchan 123 footnote 4 “Therefore, one must be especially careful with tzitzit, as it often occurs that the upper knot becomes slightly loosened. If one pulls and tightens it, there is a concern of liability of Chatas, since by tightening it one creates a “professional act,”; Toldos Shmuel Mileches Kosher 9 “I have seen with my own eyes that many stumble in this — those who tie new tzitzit (ritual fringes) onto their tallit”; Peri Megadim 317 A”A 20 brought in Ketzos Hashulchan 123 note 9; Biur Halacha 317:1 “Hakosher” that learns it is Biblically forbidden; Az Nidbaru 3:22; Beir Moshe 6:104; Rivivos Efraim 3:25; Shevet Hakehasi 1:13; SSH”K 15:7; Piskeiy Teshuvos 13:3; 317 footnote 18; 281 footnote 15;
- The melacha of koshair on Shabbos: Admur 317:1 “The Principal Prohibition: Tying and untying are amongst the principal [forbidden] actions being that in the [process of building the] Tabernacle the fishermen for the chilazon would tie and untie their nets. As all nets are made of many knots and these knots are permanent, and at times [the fishermen] would need to remove a rope from one net and add it to another net and [he would thus] untie it from [the first net] and [then] tie it [on the second net], [and thus we see that there existed both tying and untying in the works done for the Tabernacle].”; Michaber 317:1; Rambam Shabbos 10:1; Shabbos 73a and 74b
- Only permanent knots are Biblical: Admur 317:1 “Biblically one is only liable [on making] a permanent knot which is made to last forever, which means that he ties it with intention that it remain [tied] so long as it is able to exist and so long that he does not need to untie it. Now, although it is possible that he [may] need to untie it in a [very] short time and will thus untie it, nevertheless since when he ties it he does not set a date in his mind for when he will un-tie it, and it is [thus] possible that it will remain [tied] forever, [therefore] it is considered a permanent knot, and one is liable on tying it and on untying it.”; Michaber 317:1; Mishneh Shabbos 113a; Taz 317:1; M”A 317:1; Tur and Beis Yosef 317; Rashi 11b; M”B 317:1; Beis Yosef 317 in one explanation of Rashi, brought in M”A 317:1; Rabbeinu Yerucham 14:12; See P”M 317 A”A 1
- Poskim who rule a permanent knot is liable Biblically even if amateur: Opinion in Admur 317:2 “Some opinions rule that there is no difference at all between a professionally made and amateur made [knot], as even on an amateur knot one is Biblically liable if made to permanently last, and if [a knot] is designated to not last at all [then] in a situation that it is [thus] allowed to make an amateur knot then it is also allowed to make a professional knot.” Rama 317:1; Tur; Rosh 15:1, Rashi
- Poskim who rule the knot must be permanent and professional to be liable Biblically: Opinion in Admur 317:2 “There are opinions which say that one is [never] Biblically liable even on a knot that is meant to last forever unless it has been professionally done, which means that it is a strong and tough knot similar to the knots that the professionals make during their work , such as the knots of the straps for shoes and sandals which the strap makers tie at the time of making them, and the same applies for all similar cases. However, one who ties a permanent knot which is not professionally done is exempt [from liability]. For example, a strap broke and one tied it, [or a] rope tore and one tied it, or one tied a rope to a bucket or one tied an animal leash [to an animal] and so too all cases [of knots] similar to these knots which are made by amateurs [then] any person who ties them permanently is exempt [from liability].”; Michaber 317:1; Rambam Shabbos 10:1; Rif 41b
- The status of a double knot as professional: Admur 317:2 “We are therefore accustomed to be careful not to tie or untie any knot which is a double knot one on top the other even if made [in order] to undo on that same day because we are not experts as to which knots are considered professional of which are [thus] forbidden to tie and untie even if not made to last at all, and [thus] any strong knot which is very tightly tied there is doubt that perhaps this is considered a professional [knot] , and [thus since] a double knot is also a strong knot [therefore we are stringent].” Rama 317:1; Shiltei Giborim 41b Other opinions: The Shareiy Teshuvah 317:1 brings from the Bircheiy Yosef 317:1 that their custom is to allow tying a double knot to undo that day as it is considered an amateur knot, and it’s only a minority opinion which argues on this, and their opinion is nullified. However, the Kaf Hachaim 317:23 explains the Birkeiy Yosef to refer to a type of double knot that is not very tight.
- The status of Tightening Tzitzis knots as being permanent and professional knot which is Biblical: Ketzos Hashulchan 123 footnote 4 “Being that a “professional act” (ma’aseh uman) is defined when the knot is tightened. Therefore, one must be especially careful with tzitzit, as it often occurs that the upper knot becomes slightly loosened. If one pulls and tightens it, there is a concern of liability, since by tightening it one creates a “professional act,” whereas previously it was considered an unskilled knot (ma’aseh hedyot), which is not deemed a knot on a biblical level. If it had become extremely loose, such that the upper knot was somewhat distant from the knot beneath it, then even according to the Rosh it would be forbidden to tighten it. Although according to the Rosh even a non-tightened knot is considered a knot, this may only apply when it is somewhat loose but still can be undone by hand. However, when it is very loose, even according to the Rosh it is not considered a knot, due to the significant gap between the lower knot and the one above it. Therefore, it is forbidden to tighten it even slightly”; Toldos Shmuel Mileches Kosher 9 “I have seen with my own eyes that many stumble in this — those who tie new tzitzit (ritual fringes) onto their tallit (prayer shawl). It is known that when they are new, the lower knot does not hold very well and almost immediately loosens. Usually, when one checks the tzitzit before wrapping himself in the tallit, if he sees that the knot has loosened, he tightens it here and there to make it firm and properly bound. Many do not refrain from doing this even on Shabbat, and this is only due to lack of knowledge or because they do not realize the seriousness of the matter. Therefore, I saw fit to warn about this — because sometimes it could even involve a Torah-level prohibition, Heaven forbid. Blessed is the one who listens and takes heed, for good will come upon him.”; However, if done to untie that day then even to make the entire Tzitzis initially is only Rabinically forbidden. Now although one is doing so for the sake of a Mitzvah, nevertheless this was only allowed by an item that is normally eventually untied while by Tzitzis we suspect that he may leave it there forever. [Peri Megadim 317 A”A 20 brought in Ketzos Hashulchan 123 note 9] See however Biur Halacha 317:1 “Hakosher” that learns it is Biblically forbidden even if intended to undo that same day.
- The custom to hold the knot when handling Tzitzis on Shabbos to avoid tightening it: Kovetz Oholei Lubavitch 3:5 that the Rebbe showed a young married student this order of checking on Shabbos. [printed in Shulchan Menachem 1:40]
- The argument that a frequently loosening knot may not be considered permanent: This is a matter of simple logic, even if it is not explicitly stated in the sources. If a knot unravels in the vast majority of cases—within minutes or a few hours—it is difficult to classify it as a biblically permanent knot, regardless of one’s intent at the time of tying. Rather, the practical reality suggests that such a knot is not truly capable of lasting and should not be treated as a genuine enduring knot. The Az Nidbaru 3:22 leaves this matter in question and concludes that a Rabbinical prohibition it nevertheless contains
- The halachic requirements for kosher Tzitzis (minimum knots and windings): Admur 11:25-26; M”A 11:20; Menachos 39a
- The need for a double knot by Tzitzis: Admur 11:28; M”B 11:64