LEV219 Rashi there comments that "one is expected to perform the commandments only when he is sure he shall live by them, and not when in the performance of them he risks the possibility of losing his life. Therefore we may violate the Sabbath in cases of safek [uncertainty]." Maimonides' statement is the most instructive. "It is forbidden to delay violating the Sabbath for a sick person whose life is in danger, for it says, 'which if a man do them he shall live by them' and not die by them. We are thus taught that the commandments of the Torah are not intended to inflict punishment upon mankind but to bestow mercy, loving-kindness, and peace. As for the apikorsim, who say that this is a violation of the Sabbath and is forbidden, in regard to them Scripture says, 'I have given them laws which are not good, and commandments by which they cannot live'" (Ezekiel 20:25). Hilkhot Shabbat, Ch. 2, Para. 3.