וְאַ֨ךְ אֶת־דִּמְכֶ֤ם לְנַפְשֹֽׁתֵיכֶם֙ אֶדְרֹ֔שׁ מִיַּ֥ד כָּל־חַיָּ֖ה אֶדְרְשֶׁ֑נּוּ וּמִיַּ֣ד הָֽאָדָ֗ם מִיַּד֙ אִ֣ישׁ אָחִ֔יו אֶדְרֹ֖שׁ אֶת־נֶ֥פֶשׁ הָֽאָדָֽם׃
내가 반드시 너희 피 곧 너희 생명의 피를 찾으리니 짐승이면 그 짐승에게서, 사람이나 사람의 형제면 그에게서 그의 생명을 찾으리라
Mishneh Torah, Murderer and the Preservation of Life
Woher rühren diese Gesetze? Es steht geschrieben: »Wer Menschenblut vergießt, dessen Blut soll wieder durch Menschen vergossen werden« (Gen. 9:6). Diese Worte aber deuten auf Denjenigen, der selbst und ohne Hilfe eines Andern Jemanden totschlägt. Die Worte: »Das Blut in eurem Leibe werde ich fordern« (Gen. 9:5) beziehen sich auf einen Selbstmörder. »Von der Hand eines jeglichen Tieres werde ich es fordern« (ebenda.), deutet auf Denjenigen, der einen Andern den Tieren zum Zerreißen vorwirft. Die Stelle: »Von der Hand des Menschen, von der Hand seines Brudermenschen, werde ich fordern des Menschen Leben« (ebenda.), deutet auf Denjenigen hin, der Mörder einstellt, um seinen Nächsten zu erschlagen. Nun findet sich aber bei allen drei Stellen der Ausdruck »fordern«, was darauf hinweist, dass die Bestrafung solcher Verbrecher dem Himmel anheimgestellt ist.
Mishneh Torah, Rest
If a patient who is seriously ill asks for food on Yom Kippur, he should be given to eat as he desires, until he says "enough," even though competent physicians say that he does not need any food. If the patient says that he does not require food, and the physician says that he does, he should be fed in accordance with the physician's order, provided that the physician is competent. If one physician says that the patient needs food and another says that he does not, he should be given food. [If] some physicians say he needs to and others say he does not need to, we go according to the majority or [according to] the more expert ones. And this is so long as the ill person does not say, "I need [to eat]." But if he says, "I need [to eat]," we feed him. [If] the ill person does not say that he needs [to eat] and the physicians disagree and all of them were experts and those who said that he does not need to [eat] are of the same number as those who said he needs [to eat], we feed him.
Kitzur Shulchan Arukh
[The laws of] Shabbos are suspended1דְחוּיָה = suspended. More literally the word דְחוּיָה means “pushed aside,” as opposed to הוּתְּרָה —“made permissible.” There is great controversy among the poskim as to the attitude we take in permitting the transgression of Shabbos to save a life, whether it is דְחוּיָה or הוּתְּרָה. Shulchan Aruch Harav 328: 13 and this author maintain that it is דְחוּיָה and, therefore, if a method can possibly be found to minimize the transgression, such as doing the melachah with a שִׁינוּי, i.e. in an unusual manner, then that is preferable (see Sho’el U’maishiv 41, 42). Tzemach Tzedek (o.c. 38), Tashbatz (III: 37), Magein Avraham (328: 17) etc. hold הוּתְּרָה and there is no need to seek ways of minimizing the transgression. Chelkas Yoav (o.c. 14) writes that where a definite danger exists it is הוּתְּרָה, but where there is doubt as to whether the situation is life-threatening, it is דְחוּיָה. [See also Kovetz Shiurim, Kesubos paragraph 13; Biur Halacha 278: 1] where there is a life-threatening situation, as are all mitzvos in the Torah. Therefore, one who is dangerously ill and he is an observant person, though he occasionally transgresses a law because of temptation,2Either due to lack of self-control or to inconveniences. This is as opposed to one who transgresses spitefully, who, having done so twice, may not be saved if desecrating the Shabbos is necessary. and even for a day-old child,3Desecrating the Shabbos is permitted to save an unborn fetus. [Ritva, Maseches Niddah 44; B’hag; Tur 617; see also Rosh, Maseches Yoma 8: 13; Peri Megadim 328: 1; Biur Halacha 330] it is a mitzvah to violate the Shabbos to save him. [Even] if the patient refuses, we force him to accept help. It is a grave sin to carry piety to the point of idiocy, and refuse treatment because it would violate a law. About such a person is it said:4Genesis 9: 5. "Only of the blood of your lives will I demand an account." One who is quick to desecrate the Shabbos for the sake of a critically ill person, deserves praise. Even if a non-Jew is present, [every] effort should be made that a Jew do [what is necessary].5This is a matter of controversy among the poskim. Rosh, Shulchan Aruch (328: 12), Taz (ibid.) and Mishnah Berurah rule that a Jew is preferable. Rema and Shulchan Aruch Harav prefer that it be done by a non-Jew if one is available. The author agrees with the former. Any person that desecrates Shabbos for the sake of a critically ill person, even if it was found later to be unnecessary, will be rewarded. For example, if the doctor said: "This patient requires one dried fig [for cure]" and ten people ran and plucked one fig each and brought it, they all will be well rewarded by Hashem, blessed be His Name, even if the patient was cured [as a result of] the first [fig]. Similarly, in any life-threatening situation, even when the threat to life is uncertain,6V. paragraph 3. it is a mitzvah to desecrate Shabbos for him, and to do any and all d'oraisa prohibitions for him, because there is not a thing that stands in the way of a life-threatening situation. The Torah was given only for the purpose of [bringing] life, as it is said: "That man shall do them and live through them," and [the Sages] inferred: "Live through them but not to die on account of them." This holds true except for the laws concerning idolatry, illicit sexual relations and murder, where one must die rather than transgress.7V. Yoreh Dei’ah 157.