One of the expressions of a vow that appears in the Mishna is menudeh ani lekha – “my relationship with you is one of nidui.” A nidui is a type of ban, a basic type of ostracism that was used to distance a given individual from the community (more severe levels of excommunication include shamta and ḥerem). The rules and regulations of nidui, including the requirement that someone in this state avoid contact with others as well as punishments that the person is supposed to accept upon himself, are delineated in the third chapter of Massekhet Moed Katan. Nidui can be imposed on someone by the courts for a number of reasons:
- It can be used as a method of forcing someone to accept the ruling of the court.
- It can be a punishment for a transgression that the person did.
- It can be a punishment for a person who belittled or made fun of the court.
- Sometimes a Sage can put someone into nidui because he feels that the person insulted him.
Depending on the underlying reason for the nidui, we find different methods and different lengths of time necessary for releasing the person from this state.
One example brought by the Gemara is taught by Rav Hanin, who quotes Rav as teaching that someone who hears his friend take God’s name in vain must declare that he is in nidui, and that if he does not do so, then he himself will be in nidui.
Most of the commentaries understand this as simply using God’s name without purpose – even when saying a berakha that is unnecessary. The Ge’onim discuss this at some length, concluding that this holds true even if God’s name is said in a foreign language. Others, however, indicate that, in this context, taking God’s name in vain refers to a situation of a false oath.