a binding pledge of self-denial: an obligation a person ties onto their own life before God, normally a promise to go without something otherwise allowed
The word comes straight from the ordinary Hebrew verb for tying something up (אָסַר), the verb used of harnessing an animal or shackling a prisoner. Numbers 30 keeps the picture alive by using the verb and the noun together, so that a person literally "binds a binding" on their own soul. A promise, in this way of speaking, is a rope you knot around yourself.
Every use of the word sits in that one chapter, and in almost every verse it stands beside the ordinary word for a vow (נֶדֶר). The two together cover the whole field of promises a person makes to God: the vow offers God something, and this word gives something up. Numbers 30:13 spells out what giving up looks like, calling it a binding oath "to afflict oneself," which meant going without food, drink, or some other ordinary comfort.
The chapter is not really about how such a pledge is made but about who may cancel it. Because the promise is self-imposed rather than commanded, the household head who hears it has one day to respond:
- a father who hears his daughter's pledge and stays silent lets it stand
- a husband who objects on the day he hears of it cancels it, and she is not held guilty
- a woman with no father or husband over her carries her pledge with no one to cancel it
What the chapter never allows is for the person who spoke the pledge to simply walk away from it.
Disputed
Whether the noun denotes specifically a vow of abstinence, or more broadly any binding obligation a person imposes on themselves by their own word.
- majorityIt is the negative counterpart of נֶדֶר: a self-imposed prohibition, a pledge to abstain, as the qualifying phrase שְׁבֻעַת אִסָּר לְעַנֹּת נָפֶשׁ in Numbers 30:13 (Heb 30:14) indicates.; HALOT (Koehler-Baumgartner), s.v. אִסָּר; Jacob Milgrom, Numbers, JPS Torah Commentary (Philadelphia: Jewish Publication Society, 1990), on Numbers 30
- minorityIt is a general term for a bond or binding obligation assumed by one's own utterance, with abstinence only the application the chapter happens to describe.; BDB (Brown-Driver-Briggs), s.v. אִסָּר; DCH (Dictionary of Classical Hebrew), s.v. אִסָּר