Shabbat 40B

כי האי תנא:

Rabba’s statement is according to this tanna in the baraita, who referred to those who violated a rabbinic decree as transgressors.

אמבטיאות של כרכים מטייל בהן ואינו חושש. אמר רבא: דוקא כרכין, אבל דכפרים ⁠— לא. מאי טעמא ⁠— כיון דזוטרין נפיש הבלייהו.

It was taught in a Tosefta: In bathhouses in cities, one may stroll through them and, even if he sweats while doing so, need not be concerned. Rava said: This applies specifically to bathhouses in cities; but in villages, no, it does not apply. What is the reason for this distinction? Since the bathhouses in the villages are small, their heat is great, and even merely walking through them will certainly cause one to sweat.

תנו רבנן: מתחמם אדם כנגד המדורה ויוצא ומשתטף בצונן, ובלבד שלא ישתטף בצונן ויתחמם כנגד המדורה, מפני שמפשיר מים שעליו. תנו רבנן: מיחם אדם אלונטית ומניחה על בני מעים בשבת, ובלבד שלא יביא קומקומוס של מים חמין ויניחנו על בני מעים בשבת. ודבר זה אפילו בחול אסור, מפני הסכנה.

A baraita states: One may warm himself opposite a bonfire on Shabbat and emerge and rinse in cold water as long as he does not first rinse in cold water and then warm himself opposite the bonfire. This is prohibited because he thereby warms the water on his body and renders it lukewarm. The rabbis also taught: A person whose intestines are painful may heat up a towel [aluntit] and place it on his intestines even on Shabbat. This is permitted as long as one does not bring a kettle of water and place it on his intestines on Shabbat, lest the water spill and he come to wring it out (Tosafot), which is a prohibited labor on Shabbat. And placing a kettle directly on his intestines is prohibited even on a weekday due to the danger involved. If the water is extremely hot it could spill and scald him.

תנו רבנן: מביא אדם קיתון מים ומניחו כנגד המדורה. לא בשביל שיחמו, אלא בשביל שתפוג צינתן. רבי יהודה אומר: מביאה אשה פך של שמן ומניחתו כנגד המדורה. לא בשביל שיבשל, אלא בשביל שיפשר. רבן שמעון בן גמליאל אומר: אשה סכה ידה שמן ומחממתה כנגד המדורה, וסכה לבנה קטן, ואינה חוששת.

Similarly, A baraita states: One may bring a jug [kiton] full of cold water and place it opposite the bonfire on Shabbat; not so that the water will heat up, as it is prohibited to cook on Shabbat, rather to temper the cold, as one is permitted to render water less cold on Shabbat. R' Yehuda says: A woman may take a cruse of oil and place it opposite the bonfire; not so the oil will cook, rather, so it will warm until it is lukewarm. Rabban Shimon ben Gamliel says: A woman may smear her hand with oil, and heat it opposite the fire, and afterward smear her young son with the heated oil, and she need not be concerned about cooking on Shabbat.