The Lord protects the simple
In Psalm 116, verse six states: "The Lord protects the simple, I was brought low and he saved me." (שמר פתאים ה'; דלותי ולי יהושיע) According to the plain meaning of this verse, the Psalmist is expressing confidence and gratitude to the divine. This verse (and Psalm) are recited in the liturgical thanksgiving prayer, the Hallel.
In the rabbinic tradition, this verse takes on an entirely different and quite important meaning. The verse represents a principle of Jewish law (halakha) that permits people to assume various low-level risks and dangers. Risk may be taken because, as the verse states, the deity protects people who are "simple" (פתאים). In Jewish ethics and law, the principle of "The Lord protects the simple" has been applied at times to permit cigarette smoking, circumcision at inauspicious moments, bloodletting, unprotected intercourse for women perceived to be at risk, and such superstitions as the marriage of a woman whose previous two husbands had died ("isha katlanit").
- Shabtai, David. Journal of Halachah and Contemporary Society