מִצְוָה בְּיַד גּוֹאֵל הַדָּם [לַהֲרֹג אֶת הָרוֹצֵחַ] שֶׁנֶּאֱמַר (במדבר לה יט) "גֹּאֵל הַדָּם הוּא יָמִית אֶת הָרֹצֵחַ". וְכָל הָרָאוּי לִירֻשָּׁה הוּא גּוֹאֵל הַדָּם. לֹא רָצָה גּוֹאֵל הַדָּם אוֹ שֶׁלֹּא הָיָה יָכוֹל לַהֲמִיתוֹ אוֹ שֶׁאֵין לוֹ גּוֹאֵל דָּם בֵּית דִּין מְמִיתִין אֶת הָרוֹצֵחַ בְּסַיִף:

It is a commandment for the redeemer of blood [to kill the murderer] as it says, "The redeemer of blood shall kill the murderer (Numbers 35:19)." And everyone who is worthy to inherit, he is the redeemer of blood. If he does not want to be the redeemer of blood or if he is unable to kill him or if there is no redeemer of blood, the court kills the murderer by decapitation.

הָאָב שֶׁהָרַג אֶת בְּנוֹ. אִם הָיָה בֶּן לַנֶּהֱרָג הֲרֵי זֶה הוֹרֵג אֲבִי אָבִיו מִפְּנֵי שֶׁהוּא גּוֹאֵל. וְאִם אֵין לוֹ בֵּן אֵין אֶחָד מִן הָאַחִין נַעֲשֶׂה גּוֹאֵל הַדָּם לְהָמִית אֶת אָבִיו אֶלָּא בֵּית דִּין מְמִיתִין אוֹתוֹ. וְאֶחָד הַזָּכָר וְאֶחָד הַנְּקֵבָה בִּגְאֻלַּת הַדָּם:

In the case of a father, who killed his son, if the victim had a son, he kills his father's father, because he is the redeemer of blood. If, however, he doesn't have a son, none of his brothers becomes the redeemer of blood obliged to kills his father, but the courts execute him instead. The same law applies to men and women in cases of redeeming of blood.

וּמֻזְהָרִין בֵּית דִּין שֶׁלֹּא לִקַּח כֹּפֶר מִן הָרוֹצֵחַ. וַאֲפִלּוּ נָתַן כָּל מָמוֹן שֶׁבָּעוֹלָם וַאֲפִלּוּ רָצָה גּוֹאֵל הַדָּם לְפָטְרוֹ. שֶׁאֵין נַפְשׁוֹ שֶׁל זֶה הַנֶּהֱרָג קִנְיַן גּוֹאֵל הַדָּם אֶלָּא קִנְיַן הַקָּדוֹשׁ בָּרוּךְ הוּא שֶׁנֶּאֱמַר (במדבר לה לא) "וְלֹא תִקְחוּ כֹפֶר לְנֶפֶשׁ רֹצֵחַ". וְאֵין לְךָ דָּבָר שֶׁהִקְפִּידָה תּוֹרָה עָלָיו כִּשְׁפִיכוּת דָּמִים שֶׁנֶּאֱמַר (במדבר לה לג) "וְלֹא תַחֲנִיפוּ אֶת הָאָרֶץ" וְגוֹ'. (במדבר לה לג) "כִּי הַדָּם הוּא יַחֲנִיף אֶת הָאָרֶץ" וְגוֹ':

And the court is warned not to take a ransom from the murderer, even if they give all of the money in the world, and even if the redeemer of blood wishes to exempt them. For the life of this person who was killed is not the possession of the redeemer of blood but rather the possession of the Holy One Blessed be He as it says, "Do not take a ransom for the life of a murderer." And there is nothing that the Torah is more exacting about than bloodshed as it says, "You shall not pollute the land..." (Numbers 35:33) "...for blood pollutes the land...".

רוֹצֵחַ שֶׁהָרַג בְּזָדוֹן אֵין מְמִיתִין אוֹתוֹ הָעֵדִים וְלֹא הָרוֹאִים אוֹתוֹ עַד שֶׁיָּבוֹא לְבֵית דִּין וִידִינוּהוּ לְמִיתָה. שֶׁנֶּאֱמַר (במדבר לה יב) "וְלֹא יָמוּת הָרֹצֵחַ עַד עָמְדוֹ לִפְנֵי הָעֵדָה לַמִּשְׁפָּט". וְהוּא הַדִּין לְכָל מְחֻיְּבֵי מִיתוֹת בֵּית דִּין שֶׁעָבְרוּ וְעָשׂוּ שֶׁאֵין מְמִיתִין אוֹתָן עַד שֶׁיִּגָּמֵר דִּינָם בְּבֵית דִּין:

When a murderer kills willfully, he should not be killed by witnesses or observers until he is brought to court and sentenced to death, as implied by Numbers 35:12 "A murderer should not be put to death until he stands before the congregation in judgment." This law applies to all those liable for execution by the court, who transgressed and performed the forbidden act. They should not be executed until their trial is completed by the court.

בַּמֶּה דְּבָרִים אֲמוּרִים בְּשֶׁעָבַר וְעָשָׂה הֶעָוֹן שֶׁחַיָּב עָלָיו מִיתַת בֵּית דִּין. אֲבָל הָרוֹדֵף אַחַר חֲבֵרוֹ לְהָרְגוֹ אֲפִלּוּ הָיָה הָרוֹדֵף קָטָן הֲרֵי כָּל יִשְׂרָאֵל מְצֻוִּין לְהַצִּיל הַנִּרְדָּף מִיַּד הָרוֹדֵף וַאֲפִלּוּ בְּנַפְשׁוֹ שֶׁל רוֹדֵף:

When does the above apply? When the person has already transgressed and performed the transgression for which he is liable to be executed by the court. When, however, a person is pursuing a colleague with the intention of killing him - even if the pursuer is a minor - every Jewish person is commanded to attempt to save the person being pursued, even if it is necessary to kill the pursuer.

כֵּיצַד. אִם הִזְהִירוּהוּ וַהֲרֵי הוּא רוֹדֵף אַחֲרָיו אַף עַל פִּי שֶׁלֹּא קִבֵּל עָלָיו הַתְרָאָה כֵּיוָן שֶׁעֲדַיִן הוּא רוֹדֵף הֲרֵי זֶה נֶהֱרָג. וְאִם יְכוֹלִים לְהַצִּילוֹ בְּאֵיבָר מֵאֵיבְרֵי הָרוֹדֵף כְּגוֹן שֶׁיַּכּוּ אוֹתוֹ בְּחֵץ אוֹ בְּאֶבֶן אוֹ בְּסַיִף וְיִקְטְעוּ אֶת יָדוֹ אוֹ יִשְׁבְּרוּ אֶת רַגְלוֹ אוֹ יְסַמּוּ אֶת עֵינוֹ עוֹשִׂין. וְאִם [אֵינָן] יְכוֹלִין לְכַוֵּן וּלְהַצִּילוֹ אֶלָּא אִם כֵּן הֲרָגוּהוּ לַרוֹדֵף הֲרֵי אֵלּוּ הוֹרְגִין אוֹתוֹ אַף עַל פִּי שֶׁעֲדַיִן לֹא הָרַג שֶׁנֶּאֱמַר (דברים כה יב) "וְקַצֹּתָה אֶת כַּפָּהּ לֹא תָחוֹס עֵינֶךָ":

What is implied? If the rodef was warned and continues to pursue his intended victim, even though he did not acknowledge the warning, since he continues his pursuit he should be killed. If it is possible to save the pursued by damaging one of the limbs of the rodef, one should. Thus, if one can strike him with an arrow, a stone or a sword, and cut off his hand, break his leg, blind him or in another way prevent him from achieving his objective, one should do so. If there is no way to be precise in one's aim and save the person being pursued without killing the rodef, one should kill him, even though he has not yet killed his victim. This is implied by Deuteronomy 25:11-12, which states: "If a man is fighting with his brother, and the wife of one... grabs the attacker by his private parts, you must cut off her hand; you may not show pity."

אֶחָד בִּמְבוּשָׁיו וְאֶחָד כָּל דָּבָר שֶׁיֵּשׁ בּוֹ סַכָּנַת נְפָשׁוֹת. אֶחָד הָאִישׁ אוֹ הָאִשָּׁה. עִנְיַן הַכָּתוּב שֶׁכָּל הַחוֹשֵׁב לְהַכּוֹת חֲבֵרוֹ הַכָּאָה הַמְּמִיתָה אוֹתוֹ מַצִּילִין אֶת הַנִּרְדָּף בְּכַפּוֹ שֶׁל רוֹדֵף. וְאִם אֵינָן יְכוֹלִין מַצִּילִין אוֹתוֹ אַף בְּנַפְשׁוֹ שֶׁנֶּאֱמַר (דברים כה יב) "לֹא תָחוֹס עֵינְךָ":

There is no difference whether she grabs "his private parts" or any other organ that imperils his life. Similarly, the rodef may be a man or a woman. The intent of the verse is that whenever a person intends to strike a colleague with a blow that could kill him, the pursued should be saved by "cutting off the hand" of the rodef. If this cannot be done, the victim should be saved by taking the rodef's life, as the verse continues: "you may not show pity."

אַף זוֹ מִצְוַת לֹא תַּעֲשֶׂה שֶׁלֹּא לָחוּס עַל נֶפֶשׁ הָרוֹדֵף. לְפִיכָךְ הוֹרוּ חֲכָמִים שֶׁהָעֻבָּרָה שֶׁהִיא מַקְשָׁה לֵילֵד מֻתָּר לַחְתֹּךְ הָעֵבָּר בְּמֵעֶיהָ בֵּין בְּסַם בֵּין בְּיָד מִפְּנֵי שֶׁהוּא כְּרוֹדֵף אַחֲרֶיהָ לְהָרְגָהּ. וְאִם מִשֶּׁהוֹצִיא רֹאשׁוֹ אֵין נוֹגְעִין בּוֹ שֶׁאֵין דּוֹחִין נֶפֶשׁ מִפְּנֵי נֶפֶשׁ וְזֶהוּ טִבְעוֹ שֶׁל עוֹלָם:

This, indeed, is one of the negative mitzvot - not to take pity on the life of a rodef. On this basis, our Sages ruled that when complications arise and a pregnant woman cannot give birth, it is permitted to abort the fetus in her womb, whether with a knife or with drugs. For the fetus is considered a rodef of its mother. If the head of the fetus emerges, it should not be touched, because one life should not be sacrificed for another. Although the mother may die, this is the nature of the world.

כָּל הַיָּכוֹל לְהַצִּיל וְלֹא הִצִּיל עוֹבֵר עַל (ויקרא יט טז) "לֹא תַעֲמֹד עַל דַּם רֵעֶךָ". וְכֵן הָרוֹאֶה אֶת חֲבֵרוֹ טוֹבֵעַ בַּיָּם. אוֹ לִסְטִים בָּאִים עָלָיו. אוֹ חַיָּה רָעָה בָּאָה עָלָיו. וְיָכוֹל לְהַצִּילוֹ הוּא בְּעַצְמוֹ. אוֹ שֶׁיִּשְׂכֹּר אֲחֵרִים לְהַצִּילוֹ וְלֹא הִצִּיל. אוֹ שֶׁשָּׁמַע עוֹבְדֵי כּוֹכָבִים אוֹ מוֹסְרִים מְחַשְּׁבִים עָלָיו רָעָה אוֹ טוֹמְנִין לוֹ פַּח וְלֹא גִּלָּה אֹזֶן חֲבֵרוֹ וְהוֹדִיעוֹ. אוֹ שֶׁיָּדַע בְּעַכּוּ''ם אוֹ בְּאוֹנֵס שֶׁהוּא בָּא עַל חֲבֵרוֹ וְיָכוֹל לְפַיְּסוֹ בִּגְלַל חֲבֵרוֹ לְהָסִיר מַה שֶּׁבְּלִבּוֹ וְלֹא פִּיְּסוֹ. וְכָל כַּיּוֹצֵא בִּדְבָרִים אֵלּוּ. הָעוֹשֶׂה אוֹתָם עוֹבֵר עַל לֹא תַעֲמֹד עַל דַּם רֵעֶךָ:

Anyone who can save and does not save transgresses 'do not stand by the blood of your neighbour'. So too one who sees his friend drowning in the sea, bandits attacking him or a bad animal attacking him and he is able himself to save him or he could hire others to save him but he does not; one who hears idol worshippers or informers plotting harm for him or laying a trap for him and he doesn't tell his friend and inform him; or if he knows that an idol worshipper or a thug are on their way to his friend and he could appease them on behalf of his friend to change their intention and he doesn't appease him; and so too any similar case; One who does any of these transgresses 'do not stand idly by your neighbour's blood'.

הָרוֹאֶה רוֹדֵף אַחַר חֲבֵרוֹ לְהָרְגוֹ אוֹ אַחַר עֶרְוָה לְבָעֳלָהּ וְיָכוֹל לְהַצִּיל וְלֹא הִצִּיל. הֲרֵי זֶה בִּטֵּל מִצְוַת עֲשֵׂה שֶׁהִיא (דברים כה יב) "וְקַצֹּתָה אֶת כַּפָּהּ". וְעָבַר עַל שְׁנֵי לָאוִין עַל (דברים כה יב) "לֹא תָחוֹס עֵינְךָ" וְעַל (ויקרא יט טז) "לֹא תַעֲמֹד עַל דַּם רֵעֶךָ":

The one who sees a pursuer going after his friend to kill him or after a woman to rape her and is able to save [the pursued] and does not, this one has cancelled a positive commandment: "and cut off her hand" (Deut. 25:12) and has transgressed two negative commandments: "do not turn away your eyes" (Deut. 25:12) and "do not stand idly by your neighbor's blood" (Lev. 19:16).

אַף עַל פִּי שֶׁאֵין לוֹקִין עַל לָאוִין אֵלּוּ מִפְּנֵי שֶׁאֵין מַעֲשֶׂה בָּהֶן חֲמוּרִים הֵם. שֶׁכָּל הַמְאַבֵּד נֶפֶשׁ אַחַת מִיִּשְׂרָאֵל כְּאִלּוּ אִבֵּד כָּל הָעוֹלָם כֻּלּוֹ. וְכָל הַמְקַיֵּם נֶפֶשׁ אַחַת מִיִּשְׂרָאֵל כְּאִלּוּ קִיֵּם כָּל הָעוֹלָם כֻּלּוֹ:

And even though we do not give lashes on negative commandments because there are no "deeds" in them, nevertheless they are very serious, since every person who kills a soul from Israel is considered as having destroyed the entire world, and every person who sustains/establishes one soul from Israel is considered as having established the entire world.