Nedarim 10 - Should one ever vow?
In general, one should avoid making vows, simply because he may transgress them. Better do something good without a promise, or at least promise right before the deed. For this reason, a Nazir is called "a transgressor" - because he abstains from wine, and this is wrong. Now, if just for not drinking wine one is called a sinner, how much more so is one who afflicts himself with unnecessary deprivations and fasts.
If one does decide to make a vow, he has a choice of many words to use, "konam," "konach," "konas." These were created by the Sages, so that one should not use the word "korban" (sacrifice). But why not use the word "korban?" - Because he may say, "Korban to God." But let him say that! - Because he may say just "To God," thus using the name of God for no purpose. This all is the view of Resh Lakish.
However, Rabbi Yochanan says that these terms are translations of the word "korban" into foreign languages. According, these words are effective only if the user or those around him understand this particular language.
Art: A Domestic Affliction by Benjamin West