What is "neder"

In Judaism, a neder (נדר, plural nedarim ) is a declaration, using the name of God, of the acceptance of a self-made pledge, stating that the pledge must be fulfilled with the same importance as a halakha. The neder may be to fulfill some act in the future (either once or regularly) or to refrain from a particular type of activity of the person's choice. The concept of the neder and the surrounded Jewish law is described at the beginning of the parsha of Matot.

The word neder is often translated into English and other languages as a vow, but this is inaccurate: a neder is neither a vow nor an oath (known in Hebrew as "shevuah"). The simple recitation of a vow is not considered swearing an oath. There is no single word in English to describe a neder. The word "neder" is mentioned 33 times in the Pentatuach, 19 of which occur in the Book of Numbers.

Judaism views the power of speech as very strong. It is speech that distinguishes humans from animals, and has the power to accomplish a lot for better or for worse. Due to the strength of a neder, and the fact that one must absolutely be fulfilled if made, many pious Jews engage in the practice of saying "b'li neder" after a statement that they will do something, meaning that their statement is not a binding neder in the event they cannot fulfill their pledge due to unforeseen circumstances.

The most common way a neder is made is through verbal pronunciation. But according to some opinions, the performance of an act on three consecutive occasions is akin to a neder.