שֶׁלֹּא לַעֲמֹד עַל דַּם רֵעִים – שֶׁלֹּא נִמָּנַע מִלְּהַצִּיל נֶפֶשׁ מִיִּשְׂרָאֵל כְּשֶׁנִּרְאֵהוּ בְּסַכָּנַת הַמִּיתָה וְהָאֲבֵדָה וְיִהְיֶה לָנוּ יְכֹלֶת לְהַצִּילוֹ בְּשׁוּם צַד, שֶׁנֶּאֱמַר (ויקרא יט טז) לֹא תַעֲמֹד עַל דַּם רֵעֶךָ. וְאָמְרִינַן בְּסַנְהֶדְרִין (עג א) תַּנְיָא מִנַּיִן לָרוֹאֶה אֶת חֲבֵרוֹ שֶׁטּוֹבֵעַ בַּנָּהָר אוֹ חַיָּה גּוֹרַרְתּוֹ אוֹ לִסְטִים בָּאִים עָלָיו שֶׁהוּא חַיָּב לְהַצִּילוֹ בְּנַפְשׁוֹ שֶׁנֶּאֱמַר לֹא תַעֲמֹד עַל דַּם רֵעֶךָ. וְלָא מִבָּעֲיָא אַצּוֹלֵה בְּנַפְשֵׁהּ דְּמִחַיַּב, אֶלָּא מִטְרָח וּמֵיגַר נָמֵי אֲגִירֵי חַיָּב, וְעוֹד כָּלְלוּ רַבּוֹתֵינוּ ז"ל בְּאַזְהָרָה זוֹ שֶׁלֹּא לִכְבֹּשׁ עֵדוּת כְּדֵי שֶׁלֹּא יְאַבֵּד חֲבֵרוֹ מָמוֹן. וְכֵן הוּא בַּסִּפְרָא (סדר קדושים ד ח) מִנַּיִן שֶׁאִם נוֹדַע לוֹ עֵדוּת שֶׁאֵינוֹ רַשַּׁאי לִשְׁתֹּק עָלֶיהָ, שֶׁנֶּאֱמַר וְלֹא תַעֲמֹד עַל דַּם רֵעֶךָ. וּמִנַּיִן שֶׁאִם רְאִיתוֹ טוֹבֵעַ בַּנָּהָר וכו'. וּמִנַּיִן לְרוֹדֵף אַחַר חֲבֵרוֹ לְהָרְגוֹ, שֶׁאַתָּה חַיָּב לְהַצִּילוֹ בְּנַפְשׁוֹ? שֶׁנֶּאֱמַר לֹא תַעֲמֹד וְגוֹ'. To not stand over the blood of neighbors: That we not refrain from saving the soul of an Israelite when we see him in danger of death and destruction and we have the ability to save him from any side, as it is stated (Leviticus 19:16), “you shall not stand over the blood of your neighbor.” And we say in Sanhedrin 73a, “We learn, ‘From where [do we know] about one who sees his fellow drowning in a river, or being dragged away by a wild animal, or [that there are] bandits coming against him, that he is obligated to save him with his life? As it is stated, “you shall not stand over the blood of your neighbor.”’ It is not needed that he is obligated with his life, but he is also obligated to tarry and hire [others to do so].” And our Rabbis, may their memory be blessed, also included in this warning (negative commandment) not to suppress testimony so that his fellow not lose money. And so is it in Sifra, Kedoshim, Chapter 4:8, “From where [do we know] that if testimony is known to him that he is not permitted to remain silent about it? As it is stated, ‘you shall not stand over the blood of your neighbor.’ And from where [do we know] if you see someone drowning in the river, etc. And from where [do we know about] one pursuing his fellow to kill him, that you are obligated to rescue him with [the soul of the pursuer]? As it is stated, ‘you shall not stand, etc.’”
שֹׁרֶשׁ מִצְוָה זוֹ יָדוּעַ, כִּי כְּמוֹ שֶׁיַּצִּיל הָאֶחָד אֶת חֲבֵרוֹ כֵּן חֲבֵרוֹ יַצִּיל אוֹתוֹ וְיִתְיַשֵּׁב הָעוֹלָם בְּכָךְ, וְהָאֵל חָפֵץ בְּיִשּׁוּבוֹ כִּי לָשֶׁבֶת יְצָרָהּ, וּכְבָר נִתְבָּאֲרוּ דִּינֵי מִצְוָה זוֹ בְּמַסֶּכֶת סַנְהֶדְרִין (עג א). The root of this commandment is well-known — as [just] like one will save his fellow, so [too,] will his fellow save him. And the world will be inhabited like this, and God desires its habitation, as ‘He created it to be inhabited.’ And the laws of this commandment have already been elucidated in Tractate Sanhedrin.
וְנוֹהֶגֶת בְּכָל מָקוֹם וּבְכָל זְמַן בִּזְכָרִים וּנְקֵבוֹת. וְהָעוֹבֵר עָלֶיהָ וְנִמְנַע מִלְּהַצִּיל וְיֵשׁ יְכֹלֶת בְּיָדוֹ עָבַר עַל לָאו, וְאֵין לוֹקִין עָלָיו לְפִי שֶׁהוּא לָאו שֶׁאֵין בּוֹ מַעֲשֶׂה, דְּקַיְמָא לַן אֵין לוֹקִין עָלָיו. And it is practiced in every place and at all times by males and females. And one who transgresses it and refrains from saving [a Jew in danger] and has the ability [to do so] has violated this negative commandment. But we do not administer lashes for it, since it is a negative commandment that does not have an act [involved] with it — and it is established for us that we do not administer lashes [in such a case].