Halacha for Sunday 13 Iyar 5781 April 25 2021

Tying Tzitzit Strings and Plastic Cable Ties on Shabbat

In the previous Halachot we have discussed some basic laws of tying and untying knots on Shabbat. The general rule is any knot that is either “professional,” i.e. requires some skill to make, or “permanent,” i.e. is meant to last for a prolonged amount of time, is forbidden to be made on Shabbat.

Tying an Additional Knot on Top of a Knot Which Existed Before the Onset of Shabbat
We have already mentioned that some authorities rule stringently and prohibit tying a double knot on Shabbat, for this is considered a professional knot. (For instance, when one ties one’s shoes, one usually makes one knot and another bow on top of that. Making another knot on top of the first one makes the knot stronger.)

Thus, the Poskim write that if there was one knot tied before Shabbat, one should not make an additional knot on top of it, for the second knot is the primary knot forbidden on Shabbat. This is similar to a situation where one letter was written before Shabbat and writes another letter on Shabbat thereby completing the word. For instance, if the letter “Alef” was already written and one then adds the letter “Bet” on Shabbat, it is considered that one has written the word “Av” (“father” in Hebrew), a word with a meaning, on Shabbat, which is a Torah prohibition. (It is a rabbinic prohibition to write even one letter on Shabbat.)

Similarly, if one adds another knot to a pre-existing knot on Shabbat, one transgresses the forbidden work of tying on Shabbat. Maran Rabbeinu Ovadia Yosef zt”l rules likewise in his Chazon Ovadia-Shabbat, Part 5, page 68. Although we have written previously that Maran zt”l rules that one who ties a double knot on Shabbat has on whom to rely, it is nevertheless worthy to act stringently regarding this matter.

Tightening Loosened Tzitzit
If one’s Tzitzit loosened on Shabbat, one may not tighten it on Shabbat, for this resembles tying a double not. This is especially true since there is room to say that tying Tzitzit is a kind of “professional” knot and Tzitzit are considered tied “permanently” since one never intends to untie them.

Plastic Cable Ties
The modern-day Poskim discuss whether or not one may use plastic cable ties on Shabbat. Should their use pose a concern of the forbidden works of tying or building on Shabbat? Maran zt”l rules (ibid. page 75) that there is no prohibition involved and one may use them on Shabbat, for this is not considered a “knot”; rather, the plastic cable is only caught and tightened. The Torah never discussed such a reality and our Sages never banned this kind of action, for this does not resemble the forbidden work of tying at all.

Summary: One may not tighten loosened Tzitzit strings on Shabbat. One may use plastic cable ties on Shabbat.

Ask the Rabbi


8 Halachot Most Popular

Reciting Birkat Hamazon While Walking on One’s Way

Question: If one is eating while walking outdoors, may one recite Birkat Hamazon while continuing to walk? Answer: In the previous Halacha we have discussed that our Sages have enacted that one must recite Birkat Hamazon while sitting in order for the individual to have maximum concentration. ......

Read Halacha

The Significance of Tu Bishvat

The Fifteenth of Shevat or Tu Bishvat is the Rosh Hashanah for trees (Rosh Hashanah 2a). Most people commonly think that just as on the First of Tishrei, which is the day of Rosh Hashanah, all creations are judged for life or death, for wealth or poverty, and the like, so too, on Tu Bishvat, trees a......

Read Halacha

Reciting Birkat Hamazon While Seated

Question: Is one obligated to sit while reciting Birkat Hamazon or is it permissible to recite it while walking as well? Answer: The Gemara in Masechet Berachot (51b) states that one must recite Birkat Hamazon while seated. The Poskim as well as Maran Ha’Shulchan Aruch (Chapter 183) rule li......

Read Halacha

A Dish Comprised of Several Kinds of Food

Question: What is the correct blessing on stuffed peppers? Similarly, what is the correct blessing on a cake which has just a little flour but the primary ingredients of the cake are fruits and nuts? Answer: In the previous Halacha we have explained that when one eats two different foods requirin......

Read Halacha


Foods Which Contain Flour

During the past few days, we have discussed that when a dish is comprised of several different foods which require different blessings, one should recite the blessing on the primary food in the dish. Thus, if one eats grape leaves stuffed with rice, one should recite the Mezonot blessing, for the ri......

Read Halacha

The Law that the Blessing on a Primary Food Exempts a Secondary Food

Next Sunday night marks Tu Bishvat, a day we customarily recite many blessings. We shall therefore discuss the laws of blessing for the next several days. The Mishnah in Masechet Berachot (44a) states: “The rule is: If there is a primary food and a secondary food along with it, one recites ......

Read Halacha

The Laws of a Primary and Secondary Food Regarding Blessings

Question: If one eats a slice of bread along with fish, is it possible that one only recites a blessing on the fish and the bread will be considered secondary to the fish and exempted by it? Answer: In the previous Halacha we have explained the basic laws of primary and secondary foods regarding ......

Read Halacha

The Order for Lighting Shabbat and Chanukah Candles

There is a disagreement among the Rishonim as to the order of lighting Shabbat and Chanukah candles on Erev Shabbat Chanukah. The Ba’al Halachot Gedolot (commonly referred to as “Behag”) is of the opinion that Chanukah candles must be lit before Shabbat candles because women cu......

Read Halacha