[The declarations:] “Korban, I shall not eat of yours,” “Korban, [if] I shall eat of yours,” [and] “Not a korban, [what] I shall not eat of yours” —- [are] not binding.  “Shevuah, I shall not eat of yours,” “Shevuah [if] I shall eat of yours,” [and] “No shevuah, [for what] I do not eat” —- [are] binding. This is [an instance in which] oaths are more stringent than nedarim.  What is an instance in which nedarim are more stringent than oaths? [If] he said: “Konam, [the] succah that I am constructing,” “[the] lulav that I am taking,” “[the tefillin that I am wearing” —- as nedarim, [these declarations] are binding; as oaths, they are not binding, for one may not swear to transgress the commandments.

There is a neder within a neder, but there is not an oath within an oath. How? If he said: “I am a Nazirite if I eat, I am a Nazirite if I eat,” and he eats —- he is bound by each [declaration]. “Shevuah, that I shall not eat, shevuah, that I shall not eat,” and he ate —- he is liable only for one.