Shabbat 39b
שבת ל״ט ב — ד"ה אָמַר רַב אִיקָא בַּר חֲנַנְיָא
Shabbat 39b:4
Rav Ika bar Hananya explains that the mishna discusses rinsing one's entire body with water, and its ruling accords with Rabbi Shimon's position from the Tosefta, which permits rinsing with hot water heated before Shabbat but prohibits rinsing with water heated on Shabbat itself, while Rabbi Meir forbids rinsing with hot water entirely and Rabbi Yehuda permits it only with cold water.
אָמַר רַב אִיקָא בַּר חֲנַנְיָא: לְהִשְׁתַּטֵּף בָּהֶן כׇּל גּוּפוֹ עָסְקִינַן, וְהַאי תַּנָּא הוּא דְּתַנְיָא: לֹא יִשְׁתַּטֵּף אָדָם כׇּל גּוּפוֹ בֵּין בְּחַמִּין וּבֵין בְּצוֹנֵן — דִּבְרֵי רַבִּי מֵאִיר. רַבִּי שִׁמְעוֹן מַתִּיר. רַבִּי יְהוּדָה אוֹמֵר: בְּחַמִּין — אָסוּר, בְּצוֹנֵן — מוּתָּר.
Rav Ika bar Ḥananya said: In our mishna, we are dealing with water that was heated in order to rinse one’s entire body with it. Rinsing does not have the same legal status as bathing. And that which we learned in the mishna: Water that was heated on Shabbat is prohibited for bathing, from which it can be inferred that water heated before Shabbat is permitted for bathing on Shabbat, is in accordance with the opinion of this tanna, the opinion of Rabbi Shimon in the Tosefta. As it was taught in a Tosefta: One may neither rinse his entire body with hot water, even if it was heated before Shabbat, nor with cold water; this is the statement of Rabbi Meir. Rabbi Shimon permits doing so even with hot water because it was heated before Shabbat. Rabbi Yehuda says: With hot water, it is prohibited; with cold water, it is permitted. According to Rabbi Shimon, it is completely prohibited to rinse with water that was heated on Shabbat itself. Consequently, our mishna, which does not differentiate between hot and cold water, is in accordance with the opinion of Rabbi Shimon.