סימן צח סעיף ל

מֻתָּר לְחַמֵּם מַיִם לִרְחֹץ יָדָיו, אֲבָל לֹא כָּל גּוּפוֹ. וּלְצֹרֶךְ תִּינוֹק, אִם צְרִיכִין לְרָחֳצוֹ, אָסוּר גַּם כֵּן לְחַמֵּם מַיִם בִּשְׁבִילוֹ, אֲפִלּוּ עַל יְדֵי אֵינוֹ יְהוּדִי. אַךְ יְכוֹלִין לְהַרְבּוֹת בִּשְׁבִילוֹ, דְּהַיְנוּ כְּשֶׁצְּרִיכִין קְצָת מַיִם לְבִשּׁוּל, מֻתָּר לְחַמֵּם אֲפִלּוּ יוֹרָה גְּדוֹלָה, רַק שֶׁיִּתֵּן כָּל הַמַּיִם קֹדֶם שֶׁהֶעֱמִידָהּ עַל הָאֵשׁ, וְלֹא יוֹסִיף אַחַר כָּךְ. וְאִם הַתִּינוֹק חוֹלֶה קְצָת, מֻתָּר לְחַמֵּם בִּשְׁבִילוֹ עַל יְדֵי אֵינוֹ יְהוּדִי (סִימָן תקיא ובחיי"א).

It is permitted to heat water to wash your hands⁸⁵Face, hands, and feet, (Mishnah Berurah 511:9, poskim) Because this is something everyone needs to do. In our times, when people wear shoes, washing the feet may not be in this category. but not for bathing your whole body.⁸⁶Warming the water just enough to take the chill out is permitted according to some poskim. (see Sha’ar Hatziyun) If you need (warm) water to bathe a child, it is also forbidden to heat the water for him, even through a non-Jew.⁸⁷Rema. This is true according to all poskim. (Mishnah Berurah 511:13) In the event it was warmed on Yom Tov for this purpose, even by a Jew, you may bathe the child in it if he is normally bathed every day. This is forbidden for an adult, even if the water was warmed for cooking. (See Ramah, Magein Avraham and Mishnah Berurah 511:12) But you may heat a larger quantity because of him; thus when you need a little water for cooking, it is permitted to heat even a large kettle,⁸⁸And use the extra water to bathe the child. provided you pour in all the water before placing it on the fire and do not add any water after that. If the child is slightly ill, it is permitted to have the water heated for him through a non-Jew.⁸⁹Chayei Adam, Mishnah Berurah.

תנא דבי אליהו כל השונה הלכות בכל יום מובטח לו שהוא בן העולם הבא שנאמר הליכות עולם לו אל תקרי הליכות אלא הלכות (נדה ע"ג.)