These sources establish the halakhic obligation to guard against danger to life and remove hazards, drawing on biblical commandments, Talmudic principles, and medieval and later codifications. They form the foundation for evaluating whether activities that pose health risks—such as smoking—are permitted under Jewish law.
וְנִשְׁמַרְתֶּם מְאֹד לְנַפְשֹׁתֵיכֶם
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What the sources say
The foundation of the discussion is the Torah's command in Devarim 22:8 — "you shall not bring bloodguilt on your house" — which the Gemara in Bava Kamma 15b–16a extends beyond the parapet case to any maintained hazard, teaching that one may not keep a vicious dog or an unstable ladder in one's home, deriving from that same verse a general prohibition against allowing dangerous conditions to persist.
The Rambam in Mishneh Torah, Murderer and the Preservation of Life 11:4–5 codifies this as both a positive commandment — to remove any life-threatening obstacle — and a negative prohibition, grounding it in the pasuk Devarim 4:15, "be most careful for your souls," making self-endangerment a biblical violation and not merely a matter of piety.
The Shulchan Arukh in Choshen Mishpat 427 affirms this ruling without qualification: any hazard that poses a danger to life triggers the positive obligation to remove it and the transgression of "do not place blood," a standard that the Arukh HaShulchan (Choshen Mishpat 427:1–5) elaborates upon in discussing which structures and spaces fall under this duty.
Underlying all of these rulings is the principle stated by Rabbi Yannai in Shabbat 32a — that a person should never place himself in a dangerous situation relying on a miracle — establishing that deliberately courting physical risk is condemned by Chazal as a failure of responsibility, not a matter of divine trust.
דברים ד׳:ט״ו
Deuteronomy 4:15
The verse 'v'nishmartem me'od lenafshoteichem' is a core biblical source for the obligation to protect one’s life and avoid danger.
וְנִשְׁמַרְתֶּ֥ם מְאֹ֖ד לְנַפְשֹׁתֵיכֶ֑ם כִּ֣י לֹ֤א רְאִיתֶם֙ כׇּל־תְּמוּנָ֔ה בְּי֗וֹם דִּבֶּ֨ר יְהֹוָ֧ה אֲלֵיכֶ֛ם בְּחֹרֵ֖ב מִתּ֥וֹךְ הָאֵֽשׁ׃
For your own sake, therefore, be most careful—since you saw no shape when GOD spoke to you at Horeb out of the fire—
דברים כ״ב:ח׳
Deuteronomy 22:8
Requires building a parapet on a roof so that bloodguilt not come upon one's house, a classic scriptural source for removing hazards and preventing injury.
כִּ֤י תִבְנֶה֙ בַּ֣יִת חָדָ֔שׁ וְעָשִׂ֥יתָ מַעֲקֶ֖ה לְגַגֶּ֑ךָ וְלֹֽא־תָשִׂ֤ים דָּמִים֙ בְּבֵיתֶ֔ךָ כִּֽי־יִפֹּ֥ל הַנֹּפֵ֖ל מִמֶּֽנּוּ׃
When you build a new house, you shall make a parapet for your roof, so that you do not bring bloodguilt on your house if anyone should fall from it.
בבא קמא ט״ו ב-ט״ז א
Bava Kamma 15b-16a
Discusses responsibility for hazards and establishes that one may not maintain conditions that can cause injury. This sugya underlies later codifications of safety obligations.
מִדְּרַבִּי נָתָן. דְּתַנְיָא, רַבִּי נָתָן אוֹמֵר: מִנַּיִין שֶׁלֹּא יְגַדֵּל אָדָם כֶּלֶב רַע בְּתוֹךְ בֵּיתוֹ, וְאַל יַעֲמִיד סוּלָּם רָעוּעַ בְּתוֹךְ בֵּיתוֹ? תַּלְמוּד לוֹמַר: ״לֹא תָשִׂים דָּמִים בְּבֵיתֶךָ״.
The justification for this is from the ruling of Rabbi Natan, as it is taught in a baraita: Rabbi Natan says: From where is it derived that one may not raise a vicious dog in his house, and one may not set up an unstable ladder in his house? The verse states: “You shall not bring blood into your house” (Deuteronomy 22:8), i.e., one may not allow a hazardous situation or item to remain in one’s house. As long as the hazard remains, the owner is in violation of this verse and therefore the court may excommunicate him for failing to remove the danger.
שבת ל״ב א — ד"ה רַבִּי יַנַּאי בָּדֵיק וְעָבַר
Shabbat 32a:4
States that a person should not place himself in a dangerous situation and cites the principle that danger is more severe than ritual prohibitions in some contexts.
רַבִּי יַנַּאי בָּדֵיק וְעָבַר. רַבִּי יַנַּאי לְטַעְמֵיהּ, דְּאָמַר: לְעוֹלָם אַל יַעֲמוֹד אָדָם בְּמָקוֹם סַכָּנָה לוֹמַר שֶׁעוֹשִׂין לוֹ נֵס, שֶׁמָּא אֵין עוֹשִׂין לוֹ נֵס. וְאִם עוֹשִׂין לוֹ נֵס — מְנַכִּין לוֹ מִזְּכֻיוֹתָיו. אָמַר רַבִּי חָנִין: מַאי קְרָאָה? — ״קָטֹנְתִּי מִכֹּל הַחֲסָדִים וּמִכׇּל הָאֱמֶת״. רַבִּי זֵירָא בְּיוֹמָא דְשׁוּתָא לָא נָפֵיק לְבֵינֵי דִּיקְלֵי. אָמַר רַב יִצְחָק בְּרֵיהּ דְּרַב יְהוּדָה: לְעוֹלָם יְבַקֵּשׁ אָדָם רַחֲמִים שֶׁלֹּא יֶחֱלֶה, שֶׁאִם יֶחֱלֶה אוֹמְרִים לוֹ: הָבֵא זְכוּת וְהִפָּטֵר. אָמַר מָר עוּקְבָא: מַאי קְרָאָה? — ״כִּי יִפּוֹל הַנּוֹפֵל מִמֶּנּוּ״ — מִמֶּנּוּ לְהָבִיא רְאָיָה. תָּנָא דְּבֵי רַבִּי יִשְׁמָעֵאל: ״כִּי יִפּוֹל הַנּוֹפֵל מִמֶּנּוּ״ (מִמֶּנּוּ) — רָאוּי זֶה לִיפּוֹל מִשֵּׁשֶׁת יְמֵי בְרֵאשִׁית, שֶׁהֲרֵי לֹא נָפַל, וְהַכָּתוּב קְרָאוֹ ״נוֹפֵל״. אֶלָּא, שֶׁמְגַלְגְּלִין זְכוּת עַל יְדֵי זַכַּאי וְחוֹבָה עַל יְדֵי חַיָּיב.
Rabbi Yannai would examine the ferry and cross. The Gemara comments that Rabbi Yannai acted in accordance with his reasoning stated elsewhere, as he said: A person should never stand in a place of danger saying that they on High will perform a miracle for him, lest in the end they do not perform a miracle for him. And, moreover, even if they do perform a miracle for him, they will deduct it from his merits. Rabbi Ḥanin said: What is the verse that alludes to this? When Jacob said: “I am not worthy of all the mercies, and of all the truth, which You have shown unto Your servant” (Genesis 32:11), and he explains: Since You have bestowed upon me so much kindness and truth, my merits have been diminished. Similarly, the Gemara relates that Rabbi Zeira would not go out and walk among the palm trees on a day when there was a southern wind blowing due to the fear that the trees might fall on him. In a similar vein, Rav Yitzḥak, son of Rav Yehuda, said: A person should always pray that he will not become ill, as if he becomes ill they say to him: Bring proof of your virtue and exempt yourself. It is preferable for a person not to be forced to prove that he merits staying alive, as he might not be able to prove it. Mar Ukva said: What is the verse that alludes to this? As it says: “When you build a new house, then you shall make a parapet for your roof, that you bring not blood upon your house, if the fallen falls mimenu” (Deuteronomy 22:8). He explains: Mimenu, from him proof must be brought. When one falls from his previous situation, it is his own responsibility to prove his innocence and emerge unharmed. The school of Rabbi Yishmael taught: What is the meaning of the phrase: If the fallen falls from it? This person was destined to fall from that roof from the six days of Creation, it was ingrained into nature. As, although he did not yet fall, the verse calls him fallen. Nevertheless, the owner of the house is indicted for this, as merit is engendered by means of the innocent and guilt by means of the guilty.
משנה תורה, הלכות רוצח ושמירת נפש י״א:ד׳-ה׳
Mishneh Torah, Murderer and the Preservation of Life 11:4-5
Rambam codifies the duty to remove dangerous things and not leave them in a place where they may injure others. He treats danger to life as a serious halakhic concern, not merely a moral ideal.
אֶחָד הַגַּג וְאֶחָד כָּל דָּבָר שֶׁיֵּשׁ בּוֹ סַכָּנָה וְרָאוּי שֶׁיִּכָּשֵׁל בָּהּ אָדָם וְיָמוּת. כְּגוֹן שֶׁהָיְתָה לוֹ בְּאֵר אוֹ בּוֹר בַּחֲצֵרוֹ בֵּין שֶׁיֵּשׁ בּוֹ מַיִם בֵּין שֶׁאֵין בּוֹ מַיִם חַיָּב לַעֲשׂוֹת חֻלְיָא גְּבוֹהָה עֲשָׂרָה טְפָחִים. אוֹ לַעֲשׂוֹת לָהּ כִּסּוּי כְּדֵי שֶׁלֹּא יִפּל בָּהּ אָדָם וְיָמוּת. וְכֵן כָּל מִכְשׁל שֶׁיֵּשׁ בּוֹ סַכָּנַת נְפָשׁוֹת מִצְוַת עֲשֵׂה לַהֲסִירוֹ וּלְהִשָּׁמֵר מִמֶּנּוּ וּלְהִזָּהֵר בַּדָּבָר יָפֶה יָפֶה. שֶׁנֶּאֱמַר (דברים ד ט) "הִשָּׁמֶר לְךָ וּשְׁמֹר נַפְשְׁךָ". וְאִם לֹא הֵסִיר וְהֵנִיחַ הַמִּכְשׁוֹלוֹת הַמְּבִיאִין לִידֵי סַכָּנָה בִּטֵּל מִצְוַת עֲשֵׂה וְעָבַר בְּ(דברים כב ח) "לֹא תָשִׂים דָּמִים": הַרְבֵּה דְּבָרִים אָסְרוּ חֲכָמִים מִפְּנֵי שֶׁיֵּשׁ בָּהֶם סַכָּנַת נְפָשׁוֹת. וְכָל הָעוֹבֵר עֲלֵיהֶן וְאוֹמֵר הֲרֵינִי מְסַכֵּן בְּעַצְמִי וּמַה לַּאֲחֵרִים עָלַי בְּכָךְ אוֹ אֵינִי מַקְפִּיד בְּכָךְ מַכִּין אוֹתוֹ מַכַּת מַרְדּוּת:
This requirement applies to a roof, and similarly, to any place that might present a danger and cause a person to stumble and die. For example, if a person has a well or a cistern in his courtyard, he must erect a sand wall ten handbreadths high around them or make a cover for them, so that a person will not fall in and die. Similarly, it is a positive mitzvah to remove any obstacle that could pose a danger to life, and to be very careful regarding these matters, as Deuteronomy 4:9 states: "Beware for yourself; and guard your soul." If a person leaves a dangerous obstacle and does not remove it, he negates the observance of a positive commandment, and violates the negative commandment: "Do not cause blood to be spilled." Our Sages forbade many matters because they involve a threat to life. Whenever a person transgresses these guidelines, saying: "I will risk my life, what does this matter to others," or "I am not careful about these things," he should be punished by stripes for rebelliousness.
Iggerot Moshe Choshen Mishpat 2:76
Rav Moshe Feinstein addresses the permissibility of smoking and the role of danger to health, arguing from halakhic duty to avoid harmful behavior. This is one of the central responsa on the topic.
Igros Moshe is not freely available in text. This PDF surfaced in our research. Please use the feedback buttons below to help us improve.
Iggerot Moshe Yoreh De'ah 2:49
Another major responsum on smoking and health, discussing whether smoking should be treated as a prohibited dangerous practice and how one evaluates risk in halakhah.
Igros Moshe is not freely available in text. This PDF surfaced in our research. Please use the feedback buttons below to help us improve.
Iggerot Moshe Choshen Mishpat 2:8
Addresses related issues of bodily risk and responsibility, contributing to Rav Moshe Feinstein's broader legal approach to danger and self-harm.
Igros Moshe is not freely available in text. This PDF surfaced in our research. Please use the feedback buttons below to help us improve.
שולחן ערוך, חושן משפט תכ״ז
Shulchan Arukh, Choshen Mishpat 427
Rules that one must guard against danger and remove hazards from one's property, establishing a legal obligation to prevent foreseeable harm to life and body.
וכן כל מכשול שיש בו סכנת נפשות מצות עשה להסירו ולהשמר ממנו ולהזהר בדבר יפה שנאמר השמר לך ושמור נפשך ואם לא הסיר והניח המכשולות המביאים לידי סכנה ביטל מצות עשה ועובר בלא תשים דמים:
ערוך השולחן, חושן משפט תכ״ז:א׳-ה׳
Arukh HaShulchan, Choshen Mishpat 427:1-5
Explains the laws of removing hazards and the halakhic seriousness of danger, serving as an important practical Acharonim source for health-related prohibitions.
[מ"ע לעשות מעקה ולהסיר כל מכשול מרשותו ובו י"א סעיפים] מצות עשה לעשות מעקה לגגו שנאמר ועשית מעקה לגגך ולא תשים דמים בביתך ודעת הרמב"ם בפי"א מרוצח דדוקא בבית דירה אבל בית אוצרות ובית הבקר וכיוצא בהם אינו זקוק למעקה ובספרי מרבה להדיא דחייבין במעקה ויש שתירצו דעת הרמב"ם ז"ל משום דמעקה תלוי במזוזה ובמזוזה יש מחלוקת והרמב"ם פסק דפטירי ממזוזה ולפיכך פסק דפטורין ממעקה אבל לפי מה דקיי"ל ביו"ד סי' רפ"ו שחייבין במזוזה ודאי שחייבין במעקה [הגר"א] ויש מי שאומר דאף שחייבין במזוזה יכול להיות שבמעקה פטורין דכיון דאין זה תשמיש תדיר לא חיישינן לתקלה שיפול הנופל ממנו [סמ"ע] וכן כל בית שאין בה ד"א על ד"א פטורה ממעקה שאינה בכלל בית ואינה מקום דירה ואם בכולל יש ד' על ד' והיינו שהאורך יותר מד' והרוחב פחות מד' נראה דהוי מקום דירה וחייבת במעקה וגם במזוזה חייבת כמ"ש ביו"ד שם לענין מזוזה ואף החולק שם במזוזה מ"מ במעקה דהוא ספק סכנה יש להחמיר [נ"ל]: