From: Rabbi Moshe Sofer
To: Rabbi Aharon Fulda
The Chasam Sofer resolves an apparent contradiction between the Ran's principle on conditional vows and the Gemara in Nedarim 79b by arguing that in nedarim the intent of the vower is always determinative. When a husband prohibits benefit from himself upon his wife to deter her conduct, strict immediate effect is presumed; when one vows upon himself, leniency is presumed. He also defends the Taz's ruling that slaughtering an animal for a mudar hana'ah constitutes prohibited benefit.
Source: Shu"t Chasam Sofer YD §224