By Rabbi Yair Hoffman

Introduction and Foundation

The evolution of timekeeping devices has presented numerous challenges and considerations within Halacha, with each technological advancement bringing new questions to consider. Much of the following analysis is based upon information in a new article in the Ohalei Shabbos Gilyon 77-78 by Rabbi Yitzchok Rubin shlita and Rabbi Shalom Gelbar shlita. (My thanks to my brother-in-law, Rabbi Avrohom Hirsch, a prominent sofer in Yerushalayim who forwarded it to me).

Early Mechanical Watches

In the early 16th century, the development of mechanical watches revolutionized personal timekeeping through an intricate system of springs, gears, and the balance wheel. These early timepieces required daily winding to maintain their function by tightening the mainspring that powers the movement. The 1920s brought another significant advancement with the emergence of automatic mechanical watches, pioneered by British watchmaker John Harwood. These self-winding watches incorporated a weighted rotor that would swing with the natural movement of the wearer’s arm, automatically winding the mainspring and eliminating the need for daily manual winding, though this innovation presented new questions for Shabbos observance.

The Battery-Powered Revolution

The 1950s marked another milestone with the introduction of battery-powered watches. The Hamilton Electric 500, debuting in 1957, used a battery to power its movement instead of a mainspring. This technology later evolved into automatic battery-powered watches, combining traditional battery power with self-winding capabilities.

Core Gemorah Principles

The fundamental principles governing these matters derive from the Gemorah in Shabbos 48a, which discusses a case where Rav Chisda permitted returning padding to a pillow on Shabbos after it had fallen out. This ruling was challenged by a contradictory teaching which prohibited putting padding into a pillow or cushion. The Gemorah’s answer distinguishes between new padding, which is forbidden, and old padding that had fallen out, which may be returned. Rashi explains that the prohibition of inserting new padding stems from the biblical prohibition of making or fixing a vessel. This position was cited in the Mishnah Berurah (340:33), who notes that this carries a biblical prohibition. The Mishnah Berurah did not include the Rambam’s view (Chapter 22:23), which suggests the prohibition stems from a rabbinic decree to prevent one from sewing the pillow’s edges together.

The Poskim’s Clarification

The Poskim further clarified that the permission to return old padding only applies when it can be done easily without significant effort. This position regarding the effort involved in returning padding is found in Tosfos (Shabbos 48a) and the Mordechai (Shabbos 387), later cited by the Taz (317:4). From this halacha, the Poskim derived a broad principle: one may not perform a new assembly in a vessel, even when such assembly doesn’t involve the formal prohibition of building vessels. This principle led to practical applications, such as the prohibition of inserting a new shoelace into a shoe. However, if a shoelace that was previously threaded came out, it may be returned to the shoe.

The Ran’s Commentary

The Ran  (Shabbos 48a) states that it’s forbidden to transfer padding from one pillow to another. This would similarly apply to shoelaces. Rabbi Shlomo Zalman Auerbach zatzal concurred with this position, as cited in Shemiras Shabbos K’hilchasa (15:199).

Inflatable Items

Regarding inflatable items, halacha prohibits inflating rubber wheels or balls for the first time on Shabbos. However, if such an item was inflated at least once before Shabbos, it may be reinflated during Shabbos. Some authorities questioned this ruling, noting that the new air isn’t identical to the air that was previously in the item. Rabbi Shlomo Zalman Auerbach zt”l dismissed this concern, explaining that since air has no distinct form, there is no meaningful difference between one quantity of air and another.

Water-Filled Toys

The question of water-filled toys presents another consideration. These toys, which contain water and small balls where the water remains permanently and isn’t typically emptied after use, raise questions about refilling if the water accidentally spills out. The conclusion leans toward stringency, as water is considered more tangible and substantial than air, which has no physical form at all.

Battery Operation

Battery operation presents clear prohibitions on Shabbos. The placement of a battery into any device is prohibited, even when the device is turned off. This prohibition parallels the case of inserting new padding into a pillow, which carries biblical-level prohibition. The Chazon Ish (Orach Chaim 50:9) wrote that connecting an electrical circuit raises concerns of biblical prohibition, either under the category of Boneh (building) or Makeh B’Patish. If considered building, disconnecting would involve the prohibition of soser – demolishing.

Mechanical Watch Debate

Regarding mechanical watches, significant debate exists among the Poskim. The Chayei Adam (44:19) holds that winding a watch carries biblical prohibition, basing it on Rashi  in Eruvin 103a regarding fixing a harp string. However, the Chazon Ish (50:9) rejected this proof, explaining that wrapping the harp string constituted a complete act of labor, whereas winding a watch doesn’t involve any new connection. The Mishnah Berurah, while noting both positions, emphasizes the stricter opinions.

Running Watch Considerations

The discussion becomes more nuanced when considering winding a watch that is still running. The Mishnah Berurah (338:15 and in his Sha’ar HaTziyun #18) concludes that while not biblically prohibited, one should refrain from winding even a running watch. However, since the majority opinion holds that it is not biblically prohibited, there may be room for leniency in specific cases, such as for a sick person who needs to take medication at precise times when no non-Jew is available.

Automatic Mechanical Watches

Automatic mechanical watches present unique challenges. The Chazon Ish took a strict approach and prohibited wearing such watches on Shabbos (see “Dinim V’Hanhagos MiHachazon Ish.”) However, some Poskim have ruled that technically it should be permitted, particularly when the watch is already running (Rav Shlomo Zalman Auerbach zt”l cited in Shmiras Shabbos K’hilchasa chapter 28:56). Rav Moshe Feinstein zt”l offered a mid-level approach, ruling that while technically permitted, it would be appropriate for Torah scholars to adopt a stringent position (See Rabbi Aryeh Zev Ginsberg in Divrei Chachamim question #295).

Modern Battery-Powered Watches

Modern automatic battery-powered watches present more complex prohibitions. These watches are forbidden to wear on Shabbos because they involve creation of electrical current through hand movement and battery charging. An important technical analysis appears in Chut Shani (Shabbos volume 2, p. 275), which discusses whether each movement definitively creates new energy.

Solar-Powered Technology

Solar-powered watches represent the newest technological challenge. These timepieces, which charge through exposure to light and operate on batteries, should not be worn on Shabbos, even when their batteries are fully charged. The mechanism creates several halachic concerns including the creation of electrical current through light conversion, the actual operation of the watch through this newly generated current, and the fact that even when the watch could operate without the light using its stored battery power, moving it to a lit area still creates new current.

Self-Winding Watch Consensus

Regarding self-winding watches, the consensus of the poskim is that it is forbidden to wind up a stopped mechanical watch on Shabbos. The Chelkas Yaakov 1:75 permits wearing a running self-winding watch, as does Rav Shlomo Zalman Auerbach zt”l, whose opinion is quoted in Shemiras Shabbos K’hilchasah 28, note 57. Additional support comes from Shulchan Shlomo 308:47-2, Tzitz Eliezer 9:20, and Rav Elyashiv zt”l, as quoted in Shalmei Yehudah 2, note 24. However, some poskim take a more stringent approach, including Rav Vosner zt”l in his  Shevet haLevi 3:97 and Orchos Shabbos 26, note 69.

Smart Watches

Smart watches that monitor body functions require special consideration. Rav Elyashiv zt”l (quoted in Me’or ha-Shabbos, vol. 4, p. 337) rules that unless medically necessary, such watches should not be worn on Shabbos. For watches with button-activated lights, Rav Shlomo Zalman Auerbach zt”l (ibid pg. 340), rules that if the time cannot be seen without the light, the watch may not be worn or moved at all.

Eruv Considerations

Regarding wearing watches outside areas without an eruv, three main positions exist. The first, more permissive view considers watches worn directly on the wrist as garments (malbush), held by the Igros Moshe O.C. 1:111 and 5:24. A middle ground position allows wearing gold watches as beautiful accessories (tachshit), supported by the Chelkas Yaakov O.C. 1:89 and Yechaveh Da’as 3:23. The majority opinion, however, forbids wearing all wrist watches outside, supported by the Ketzos ha-Shulchan 115, note 28, Minchas Yitzchok 1:67, Tzitz Eliezer 11:28, and Chut Shani 88:2.

Stopped Watch Status

Regarding stopped watches, the majority view, held by the Minchas Shabbos 80:242 and 88:23, as well as Rav Y.S. Elyashiv, considers a watch that stopped running as muktzeh. However, the Tzitz Eliezer 9:20 questions this ruling. An exception exists if the watch also serves as jewelry.

Wearing Women’s Clothing

The question of men wearing wristwatches relates to the broader prohibition of “lo yilbash” – the Torah’s prohibition against wearing clothes of the opposite gender, as codified in the Shulchan Aruch (Yoreh De’ah 182:5). While the prevailing halachic opinion permits men to wear wristwatches, holding that this does not violate the prohibition of “lo yilbash,” there exists a notable stringent view advocated by several prominent poskim.

This stringent approach was particularly championed by HaGaon HaRav Chaim Kanievsky zt”l, who followed the practice of both the Chazon Ish and the Steipler in refraining from wearing wristwatches. When giving brachos and guidance to those who sought his counsel, Rav Chaim would often suggest accepting various spiritual improvements, including abstaining from wearing wristwatches due to “lo yilbash” concerns. Notably, when presented with photographs of Rav Shach zt”l and Rav Elyashiv zt”l wearing watches, Rav Kanievsky explained that he himself had previously worn a watch until receiving reliable testimony from the Chazon Ish regarding its prohibition.

What people who wore watches used to do was take off their watch before they entered Rav Chaim’s presence.  Although unverified, word on the street was that Rav Chaim could tell who was accustomed to wearing a watch by looking at the difference in hairs between the left and right wrist of his visitors.

The author can be reached at [email protected]