לֹ֥א תַעֲמֹ֖ד עַל־דַּ֣ם רֵעֶ֑ךָ אֲנִ֖י יהוה׃
You shall not stand by [the shedding of] your fellow's blood. I am the Lord.
לֹֽא־תִרְאֶה֩ אֶת־שׁ֨וֹר אָחִ֜יךָ א֤וֹ אֶת־שֵׂיוֹ֙ נִדָּחִ֔ים וְהִתְעַלַּמְתָּ֖ מֵהֶ֑ם הָשֵׁ֥ב תְּשִׁיבֵ֖ם לְאָחִֽיךָ׃ וְאִם־לֹ֨א קָר֥וֹב אָחִ֛יךָ אֵלֶ֖יךָ וְלֹ֣א יְדַעְתּ֑וֹ וַאֲסַפְתּוֹ֙ אֶל־תּ֣וֹךְ בֵּיתֶ֔ךָ וְהָיָ֣ה עִמְּךָ֗ עַ֣ד דְּרֹ֤שׁ אָחִ֙יךָ֙ אֹת֔וֹ וַהֲשֵׁבֹת֖וֹ לֽוֹ׃
You shall not see your brother's ox or sheep straying, and ignore them. [Rather,] you shall return them to your brother. But if your brother is not near you, or if you do not know him, you shall bring it into your house, and it shall be with you until your brother seeks it out, whereupon you shall return it to him.
מניין לרואה את חברו שהוא טובע בנהר או חיה גוררתו או לסטין באין עליו שהוא חייב להצילו ת"ל לא תעמוד על דם רעך והא מהכא נפקא מהתם נפקא אבדת גופו מניין ת"ל והשבותו לו אי מהתם הוה אמינא ה"מ בנפשיה אבל מיטרח ומיגר אגורי אימא לא קמ"ל
From where is it derived that one who sees another drowning in a river, or being dragged away by a wild animal, or being attacked by bandits, is obligated to save him? The verse states: “You shall not stand idly by the blood of another” (Leviticus 19:16). The Gemara asks about this derivation: But is this really derived from here? It is derived from there, i.e., from a different verse, as it is taught: The Torah teaches that one must return lost property to its rightful owner. But from where is it derived that one must help his neighbor who may suffer the loss of his body or his health? The verse states: “And you shall restore it [vahashevato] to him [lo]” (Deuteronomy 22:2), which can also be read as: And you shall restore him [vehashevato] to him, i.e., saving his body. Consequently, there should be no need for the additional verse: “You shall not stand idly by the blood of another.” The Gemara answers: If this halakha were derived only from there, I would say that this matter applies only to saving the person in danger by himself, i.e., that he himself must come to his neighbor’s rescue if he can, as is the halakha with regard to returning a lost item. But to trouble himself and hire workers for this purpose, one might say that he is not obligated, just as he is not obligated to hire workers to recover another’s lost item. Therefore, the verse “Do not stand by the blood of another” teaches us that he must even hire workers, and he transgresses a prohibition if he does not do so.
א"ר זירא אמר רב הונא במצוה עד שליש מאי שליש אילימא שליש ביתו אלא מעתה אי איתרמי ליה תלתא מצותא ליתיב לכוליה ביתיה אלא אמר ר' זירא בהידור מצוה עד שליש במצוה
§ Rabbi Zeira says that Rav Huna says: For the purchase of an object with which to fulfill a mitzva, one should spend up to one-third. The Gemara asks: To what does this one-third refer? If we say it means that one should spend up to one-third of his estate to perform a mitzva, but if that is so, and if it happened to him that he became obligated in three mitzvot at the same time, should he give his entire estate away in order to fulfill those mitzvot? One is certainly not required to do so. Rather, what Rabbi Zeira said is that for the embellishment of the performance of a mitzva, e.g., to purchase a more beautiful item used in the performance of a mitzva, one should spend up to one-third more than the cost of the standard item used to perform the mitzva.
משמע דאפילו למצוה עוברת כאתרוג וסוכה אינו מחויב לתת אפילו שליש ממונו וזה תימה היאך נתנו [קצבה] למצוה עוברת וכתב הראב"ד כדי שלא יבא לידי עוני ויפיל עצמו על הצבור וכמו שאמרו עשה שבתך חול ואל תצטרך לבריות וכן אמרי' (כתובות נ.) המבזבז אל יבזבז יותר מחומש מפני שהעוני כמיתה ומיהו מסתברא דלא אמרי' הכי אלא במצות עשה משום דשב ואל תעשה שאני אבל במצות לא תעשה את כל הון ביתו יתן קודם שלא יעבור עליה.
It's understood that even for a mitzvah whose time will elapse like an etrog or a sukka one is not obligated to give even a third of his acids. It's a wonder why did they give a limit for a mitzvah whose time will elapse? The Ravad explains in order that he should not become poor and the community will be responsible, Like our sages said “Make your Shabbat like an ordinary weekday and do not be beholden to other beings” and they also said "One who dispenses [money to charity] should not dispense more than one-fifth [of their wealth]" because poor is like death however this specifically applies to a positive mitzvah since it is different “sitting and doing nothing” However, regarding a negative mitzvah, one should spend all of their wealth rather than sin.
ואם יוכל להציל עצמו בכל אשר לו צריך ליתן הכל ולא יעבור לא תעשה
If he can save himself with all he has, he must give it all rather than transgress one of the negative commandments
מי שאין לו אתרוג או שאר מצוה עוברת אין צריך לבזבז עליה הון רב וכמו שאמרו המבזבז אל יבזבז יותר מחומש אפי' מצוה עוברת ודוקא מצות עשה אבל לא תעשה יתן כל ממונו קודם שיעבור
Somebody who doesn't have an etrog or some other [objected associated with a] mitzvah whose time will elapse need not dispense much wealth on it, as they said, "One who dispenses [money to charity] should not dispense more than one-fifth [of their wealth]" even with respect to a mitzvah with a time that will elapse. This specifically applies to a positive mitzvah. However, regarding a negative mitzvah, one should spend all of their wealth rather than sin.
ואם יש סכנת אבר צ"ע אי דמי לממון או לנפש עיין בריב"ש סי' שכ"ו ובא"ח סימן שכ"ח סי"ז ונראה לקולא:
If there is a danger to an organ, we analyze if the organ is similar to money or to a person, seemingly we should be lenient.
יש דבר מצוה לכל אדם להגיד לשופט פלוני הכה פלוני ועוד הולכים בכעסם תעשה כך שלא יוסיף עוד, ואם יעליל השופט עליו ויקח כל אשר לו פטור המגיד דאל"כ אין לך אדם מציל את חבירו מיד מכהו.
ודאי אם יכול להצילו באחד מאבריו יעשה כרב הונא דקץ ידא או שמא יותר טוב שיגיד לשופט ויפסיד ממון מלחסרו אחד מאבריו והא רפיא
MENAHEM OF MERSEBURG
Certainly, if he can save another Jew by destroying one the instigator limbs he should do that. Or, perhaps is it better for him to tell the judge and lose all his money then to destroy the instigator's limb.
It is undecided.