May I tie a knot at the end of my tzizis, after all it is not a double knot?

In the previous Shabbos sheet we mentioned that the poskim hold that a strong double knot is classified as a craftsman’s knot due to its sturdiness and strength; hence one may not tie a double knot even for less than 24 hours. [1]

On the other hand, a single knot is not classified as a knot at all and may be tied for an unlimited time. However, one must be careful to know which knot the halacha considers a single knot before tying any seemingly ‘innocent’ knots. 

The permitted single knot is the knot beneath the bow on one’s shoe (without the bow). Such a knot cannot last at all and is not strong. For example, tying two handles of a plastic bag in the same manner as the knot on a shoe (we are not referring the knot where the two handles are twisted into one and tied, that comes later). Since this is only a single knot and if one were to apply any pressure to the bag the knot would open.

Such a knot may be tied for an unlimited time.

The forbidden single knots include a single knot tied into the middle of a string, the knot tied at the ends of one’s tzizis to prevent them from unraveling, two handles twisted into one, forming a loop and threading the head through the loop and the knot tied at the end of a sewing thread. Seeing that these knots can be tight and strong they share the same characteristics as the double knot and are forbidden to tie on Shabbos.

Being that the forbidden single knot is classified as a craftsman’s knot (similar to the double knot) it is forbidden to tie it even if one intends untying it within 24 hours.

Would I be permitted to untie such a knot?

Untying knots is the parallel of tying knots and any knot prohibited to tie is also prohibited to untie. Therefore one is forbidden to untie the knot at the end of his tzizis. If one sturdily tied the handles of a plastic bag either in a double knot or by twisting the handles through a loop and pulling tight it would be forbidden to open such a bag on Shabbos. It is permitted to rip open the bag – but that is another issue.

If one must tie a knot on Shabbos, either for the sake of a mitzvah or for safety reasons, is he permitted to do so?

The Shulchan Aruch says [2] that when necessary, for the sake of a mitzvah, one is permitted to tie a knot that would normally be forbidden mid’rabanan. [3] This is not a blanket heter because the Magen Avraham [4] says that this is on condition that a normal permitted knot would not suffice.

For example, one may tie a rope to fence off a hole in the ground to prevent people from getting hurt. Tying a slipknot or a bow, which are permitted knots, would not suffice as it leaves potential danger; rather one is permitted to tie a craftsman’s knot with the intention of leaving it tied for a short time. Such a knot is normally ossur mid’rabanan, but to facilitate for a mitzvah Chazal permitted it.

If the answer to the above is yes, is there a restriction as to which type he may tie and which knot not?

One may not tie a knot which is forbidden mid’oraisso (a Biblical prohibition) even for the sake of a mitzvah. Therefore a permanent double knot or any other craftsman’s knot is forbidden under all circumstances.

The P’ri Megadim raised an interesting question. Since one is permitted to tie a knot, which is only rabbinically forbidden, for the sake of mitzvah, why then if one’s tzizis tore on Shabbos, or if he does not possess a garment with tzizis is he forbidden to make tzizis on Shabbos? The solution supposedly would be to tie the tzizis intending to untie them after Shabbos, thereby only tying a knot rabbinically forbidden being that it is not a permanent one.

The Bi’ur Halacha [5] explains the matter saying that one does not look at the individual’s intention rather at the global manner of tying those particular knots. Since knots tied in tzizis are always permanently tied, it would not help deciding or intending to untie them after Shabbos and they remain knot that are biblically forbidden to tie on Shabbos. Therefore there is no option on Shabbos but to remain without tzizis on that Shabbos.

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[1] Rama at the end of simon 317:1.

[2] Simon 317:1.

[3] The מאיר בית says that this halacha is only according to the Rif and the Rambam but according to Rashi and Tosefos such a knot is ossur even for the sake of a mitzvah. This is quoted but M”B 317:13. The Shulchan Aruch HaRav and other poskim did not mention this מאיר בית . See also the SS”K 15:49 in footnote 162.

[4] See M”B 317:12.

[5] B”H simon 317:1 ‘הקושר’.