chumra

A khumra (; pl. חומרות, khumrot) is a prohibition or obligation in Jewish practice that exceeds the bare requirements of Halakha (Jewish laws). One who imposes a khumra on him- or herself in a given instance is said to be makhmir. The rationale for a khumra comes from Deuteronomy 22:8, which states that when one builds a house, he must build a fence around the roof in order to avoid guilt should someone fall off the roof. This has been interpreted by many as a requirement to "build a fence around the Torah" in order to protect the mitzvot.