The Gemara (Shabbat 40a) explains the origin of the prohibition very clearly. This is not a Torah prohibition against sweating on Shabbat. It is a rabbinic gezeirah connected specifically to the מרחץ, the bathhouse.
Originally, bathing in hot water that had been heated before Shabbat was permitted. The problem arose because בלנים היו מחמין חמין בשבת ואומרים מערב שבת הוחמו — bathhouse attendants were heating the water on Shabbat and claiming that it had been heated before Shabbat. Chazal therefore prohibited bathing in hot water. They initially continued to permit entering the bathhouse merely to sweat. But people then abused that permission as well: ועדיין היו רוחצין בחמין ואומרים מזיעין אנחנו — “they continued bathing in hot water and said, ‘We are only sweating.’” Chazal therefore prohibited entering the bathhouse even for the purpose of sweating.
This history is critical to understanding the halacha. There is no independent prohibition against sweating on Shabbat. The Shulchan Aruch (O.C. 326:12) states precisely: אסור ליכנס למרחץ אפילו להזיע — “It is forbidden to enter a merchatz, even in order to sweat.” He does not say אסור להזיע בשבת, that it is forbidden to sweat on Shabbat.
A מרחץ was a particular type of bathhouse. Its operation centered around heating large quantities of water, traditionally by maintaining a fire, and providing hot bathing facilities. The entire gezeirah developed because of the possibility and actual practice of water being heated on Shabbat and people circumventing the prohibition.
A modern sauna or steam room is not automatically a מרחץ merely because people become hot and sweat there. A dry sauna makes the distinction particularly obvious: there need not be any bathing water at all. Its function is simply to provide a hot room in which people sit and sweat.
The same is true of an ordinary modern steam room. Most steam rooms have a water faucet or hose, often used for rinsing the benches or adding water as needed. That does not transform the room into a bathhouse. The function of the room remains sitting in steam and perspiring; it is not a facility for bathing in heated water. The showers and actual bathing facilities are ordinarily elsewhere.
A traditional Turkish or Moroccan hammam gives us a much better modern picture of what a merchatz was: an establishment organized around hot bathing, heated water, steam, washing, and the associated facilities. Even today’s hammams are technologically different from those of Chazal, but conceptually they are much closer to the institution with which the gezeirah was concerned.
Most importantly, we do not simply expand a rabbinic gezeirah because a new activity seems similar. אין לנו להוסיף על הגזירה. Chazal prohibited entering a merchatz even to sweat because “I am only going in to sweat” had become the means by which people circumvented the prohibition against bathing there. They did not establish a general prohibition against entering any hot room or deliberately causing oneself to perspire.
Therefore, a modern sauna or dedicated steam room should not become a merchatz merely because people sweat there, or because there happens to be a faucet in the room. If the facility is operating continuously or automatically from before Shabbat, or is operated for the general public by non-Jews, there is no reason on account of the gezeirah of זיעה במרחץ alone to prohibit entering it.
This conclusion addresses only the law of מרחץ וזיעה. One must separately determine that the particular facility does not involve a Shabbat problem caused by the person’s use, such as activating a heater, steam generator, or other system upon entering or opening the door. Those are independent questions and should not be confused with the rabbinic gezeirah of merchatz.
You mentioned before that you can exercise on Shabbat if you need it for your health or if you enjoy it. Under those premises, can you go to the gym on Shabbat for workout or swimming?
And if the answer is yes. It is fine to have a shower in the gym?
Thank you Rabbi for the clear and detailed answer. Really appreciate it.
The Gemara (Shabbat 40a) explains the origin of the prohibition very clearly. This is not a Torah prohibition against sweating on Shabbat. It is a rabbinic gezeirah connected specifically to the מרחץ, the bathhouse.
Originally, bathing in hot water that had been heated before Shabbat was permitted. The problem arose because בלנים היו מחמין חמין בשבת ואומרים מערב שבת הוחמו — bathhouse attendants were heating the water on Shabbat and claiming that it had been heated before Shabbat. Chazal therefore prohibited bathing in hot water. They initially continued to permit entering the bathhouse merely to sweat. But people then abused that permission as well: ועדיין היו רוחצין בחמין ואומרים מזיעין אנחנו — “they continued bathing in hot water and said, ‘We are only sweating.’” Chazal therefore prohibited entering the bathhouse even for the purpose of sweating.
This history is critical to understanding the halacha. There is no independent prohibition against sweating on Shabbat. The Shulchan Aruch (O.C. 326:12) states precisely: אסור ליכנס למרחץ אפילו להזיע — “It is forbidden to enter a merchatz, even in order to sweat.” He does not say אסור להזיע בשבת, that it is forbidden to sweat on Shabbat.
A מרחץ was a particular type of bathhouse. Its operation centered around heating large quantities of water, traditionally by maintaining a fire, and providing hot bathing facilities. The entire gezeirah developed because of the possibility and actual practice of water being heated on Shabbat and people circumventing the prohibition.
A modern sauna or steam room is not automatically a מרחץ merely because people become hot and sweat there. A dry sauna makes the distinction particularly obvious: there need not be any bathing water at all. Its function is simply to provide a hot room in which people sit and sweat.
The same is true of an ordinary modern steam room. Most steam rooms have a water faucet or hose, often used for rinsing the benches or adding water as needed. That does not transform the room into a bathhouse. The function of the room remains sitting in steam and perspiring; it is not a facility for bathing in heated water. The showers and actual bathing facilities are ordinarily elsewhere.
A traditional Turkish or Moroccan hammam gives us a much better modern picture of what a merchatz was: an establishment organized around hot bathing, heated water, steam, washing, and the associated facilities. Even today’s hammams are technologically different from those of Chazal, but conceptually they are much closer to the institution with which the gezeirah was concerned.
Most importantly, we do not simply expand a rabbinic gezeirah because a new activity seems similar. אין לנו להוסיף על הגזירה. Chazal prohibited entering a merchatz even to sweat because “I am only going in to sweat” had become the means by which people circumvented the prohibition against bathing there. They did not establish a general prohibition against entering any hot room or deliberately causing oneself to perspire.
Therefore, a modern sauna or dedicated steam room should not become a merchatz merely because people sweat there, or because there happens to be a faucet in the room. If the facility is operating continuously or automatically from before Shabbat, or is operated for the general public by non-Jews, there is no reason on account of the gezeirah of זיעה במרחץ alone to prohibit entering it.
This conclusion addresses only the law of מרחץ וזיעה. One must separately determine that the particular facility does not involve a Shabbat problem caused by the person’s use, such as activating a heater, steam generator, or other system upon entering or opening the door. Those are independent questions and should not be confused with the rabbinic gezeirah of merchatz.
Hello Rabbi,
You mentioned before that you can exercise on Shabbat if you need it for your health or if you enjoy it. Under those premises, can you go to the gym on Shabbat for workout or swimming?
And if the answer is yes. It is fine to have a shower in the gym?
Yes and Yes!