28. The Three Cardinal Sins

Yesodei HaTorah 5:7

What is the source that idolatry, sexual immorality and murder should not be committed even to save a life? Deuteronomy 6:5 tells us, “You shall love Hashem, your God, with all your heart, with all your soul and with all your might.” “Your soul” means even at the cost of one’s soul. This precludes idolatry. Regarding murder to save a third party or to save one’s self from another who is coercing him, it is logical that one person’s life cannot be sacrificed for another’s. Regarding sexual immorality, the Torah compares forbidden sexual relations to murder in Deuteronomy 22:26, where it says regarding rape that “this is just like a case where one person rises up against another to kill him.”

Yesodei HaTorah 5:8

When is the rule that one may be healed by violating prohibitions (other than the three cardinal sins) only when his life is at risk? When one derives enjoyment from the prohibition, such as eating non-kosher creatures, or eating chometz on Pesach, or eating at all on Yom Kippur. But what if one does not derive enjoyment from the prohibition, such as if one makes a compress of chometz on Pesach or from other forbidden foods, or if one is given a bitter medicine mixed with forbidden foods? In such a case, since one derives no enjoyment from the prohibition, it is permitted even when if his life is not in danger. There is an exception, however: produce that was grown intermingled in the field (kilei hakerem) and meat-and-milk combinations are prohibited even in a way that does not provide enjoyment. Therefore, these may not be used in a cure even in a way that does not give enjoyment except in a case of danger to life.