Nedarim, Chapter One, Mishnah Four
The first three sections of this mishnah teach that instead of stating korban a person can name different types of sacrifices and his vow will still be effective.
The final section of the mishnah teaches that a person can make parts of his body forbidden to other people.
1) If one says A korban, A wholly burnt-offering, A meal-offering, A sin-offering, A thanksgiving-offering, A peace-offering, should be that which I eat from you he is bound [by his vow].
a) Rabbi Judah permitted [him].
2) [If he says] The korban, like a korban, korban, should be that which I eat from you he is bound [by his vow].
3) If he says, That which I shall not eat of yours should be a korban, Rabbi Meir forbids [him].
4) If one says to his fellow, Konam be my mouth which speaks with you, My hands which work for you [or] My feet which walk with you, he is forbidden.
Section one: In this section, instead of just stating korban, the person vowing names other types of sacrifices. The mishnah teaches that these are equally effective in forming vows. Rabbi Judah holds that since he didnt say like a , the vow is not valid.
Section two: All of these ways of phrasing a vow are also valid.
Section three: In this case the person adds an additional negative to his statement. Instead of saying that which I eat from you should be a korban, he says that which I shall not eat . Hence we might have interpreted the vow to meant that that which he doesnt eat should be a korban, but that which he does eat should be permissible. Nevertheless Rabbi Meir rules that it is a valid vow, for the statement could also be interpreted to mean, Your food is a korban to me, therefore I shall not eat from yours.
Section four: In these cases instead of stating that a certain object shall be prohibited, the person states that a certain part of his body shall not do something for his friend. Now usually one cannot make a prohibitive vow on an action. Prohibitive vows are only effective on things and not on intangibles. However, a person can make a prohibitive vow on a part of his body, since parts of bodies are things. For instance one can say Konam be my mouth to you, but not Konam be my speech to you; mouths have substance but speech does not.