Nedarim 2a - Introduction

Mazal Tov on Kesubos!

As an intro to nedarim i think it is very worthwhile going through the sefer hachinuch (not even the minchas chinuch) on mitzvah 30 of "lo sisa" in the aseres hadibros. He elaborates about the difference between nedarim and shavuos. We know from the gemara on 2b that nedarim are an issur cheftzah whereas shavuos are an issur gavrah. This is why a neder can only be chal on an object but cannot be used to make a commitment whereas a shavua can be used to commit to doing something. This is also the reason that a neder is not chal on a preexisting neder, nor is a shavua chal on a preexisting shavua, but a neder can be chal on a shavua and visa versa. For this same reason if one is obligated to do a mitzvah such as eating matzah, that is a chiyuv on the gavra, so he can make a neder to assur the matzah, but cannot make a shavua not to eat since he is already mushbah v'omed so it is like a shavua on a shavua.

Another distinction is that a shavua by definition invokes the name of Hashem, whereas a neder has nothing to do with the name of Hashem. The Chinuch explains that a shavua is:

שגומר האדם בלבו ואומר בפיו להיות מקיים אותו דבר שנשבע עליו ולא ישנהו לעולם כמו שהשם ברוך הוא קיים ולא ישתנה לעדי עד

Although the Ran proves that a shavua is binding if one used the language of shavua or a kinuy even if he didn't use the name of Hashem, it seems that nevertheless a shavua invokes the name of Hashem as if it were said. Based on this we can understand how one violates "lo sisa" through a shavuas shav even though the name of Hashem was not used. However, a neder does not at all invoke the name of Hashem, rather it is a power to be makdish something with one's speech and make it assur like a korban so long as either the object is owned by the madir or the subject that becomes assur is the madir. Also the Chinuch indicates that breaking a shavua is like denying Hashems eternal existence and therefore their should not be anyway to break it - the ability to be matir a shavua with charata or a pesach is a chesed of Hashem, whereas by a neder the concept of being matir it with charata is more natural and not a special chesed of Hashem.