Terumos chapter 3, mishnah 8. We have just finished discussing the importance of the verbal declaration as opposed to the physical separation of the various tithes: designating the name is a verbal declaration that takes effect and takes hold even before any physical separation of the portion from the pile. Now the question we mentioned arises: what is the law when, at the moment of designating the name, a person used wording that was a slip of the tongue, and did not refer to the piece he intended? For example, two grapes were before him, and he meant to say about one of them "this is Terumah," but mistakenly said it about the other; or he said "north" instead of "south." He did not say what he intended; rather, a slip of the tongue escaped his lips. Are his words binding, and has the object now become Terumah?
The requirement that "his mouth and his heart be in agreement":
The answer is no. There is a requirement that the mouth - what a person says - and the heart - what is in his heart - be equal and aligned with one another. If it was in his heart, meaning in his mind ("heart" here means mind), to intend one thing, and he mistakenly said something else, his words are not binding.
Terumah as "kodashim" in an abbreviated version:
The mishnah is about to discuss four types of declarations. As was mentioned in the introduction, Terumah is a sort of kodashim in an abbreviated version. Ordinary foods do not become tamei beyond two levels, up to second degree tumah; but Terumah, because of its special sanctity, can become tamei even at a third degree. Kodashim - the foods and animals offered on the altar - can become tamei even at a fourth degree. It turns out that Terumah is a level below full kodashim: abbreviated kodashim, since it has only three levels.
But the real reason Terumah is a kind of lighter kodashim is that the power that creates Terumah - the verbal power in a person's mouth - is derived from that very same source. The Torah authorizes a person to transform something that is chullin, unconsecrated, into hekdesh. When he says "this cow shall be an olah offering," his declaration is binding: it creates a prohibition, and it brings upon that cow a sanctity from which there is no way back. From now on all sorts of restrictions apply to it, and there are severe consequences if something improper is done with it.
It emerges that a person's power to make a verbal statement with binding and sanctifying status stems from his power to declare something an offering. This power appears in halachah in four different forms - four ways in which a person speaks and creates new statuses and prohibitions, and all of them derive from his power to create hekdesh through speech.
The four categories discussed in the mishnah:
Terumos and maasros - the separation itself.
Vows of hekdesh - making something into an offering, a meal offering, and the like.
Oaths - a person who swears to do something or not to do it, or who swears that something happened or did not happen. His oath is binding and has consequences.
Vows of prohibition - a person who forbids an object to himself for benefit, as though it were an offering from which one may not benefit. One who says "I will not derive benefit from this table" - from now on it is forbidden for him to sit at that table and the like.
In all four categories the law is the same: if a person tried to make a verbal declaration that changes the status of something and renders it hekdesh and forbidden, and he did not say what he intended - his words do not take effect. And all of this is for one reason: the requirement that a person's heart and mouth be aligned.
The source of this law in the verses:
The way we know that a person needs his mouth and his heart to be aligned (and "his heart" means his mind) is from two verses that appear to contradict one another. The first: "Motza sefasecha tishmor" - what has come out of your mouth you must fulfill and carry out in matters of this kind. The second, which we mentioned at the beginning of the tractate from the opening verses of Parshas Terumah in the book of Shemos, speaks of "kol nediv lev" - anyone whose spirit moves him to give. These verses also impose limitations: as we recall, a shoteh cannot separate Terumah, since he has no heart, that is, no sufficient mind, to be one who volunteers and gives of his own.
So we have two verses before us: one speaks of "motza sefatecha tishmor" - that what leaves a person's mouth is what binds him, while the other establishes that the matter must take place in the heart, that the impulse and the motivation come from the will in his heart and mind. How do we reconcile them? Does the separating and the giving take place through the action of the mouth or through the action of the heart? The answer is that both are required together: the heart and the thought join the mouth and are aligned with it.
Let us turn to the language of the Mishnah:
"HaMiskaven lomar Terumah v'amar ma'aser, ma'aser v'amar Terumah" - he intended to say of this grape that it should be Terumah, and by mistake the word "ma'aser" came out of his mouth, or the reverse. This is the first category.
"Olah v'amar shelamim, shelamim v'amar olah" - he intended to say that this cow should be an olah offering, and by mistake he said "shelamim" (a peace offering), or the reverse. These are vows of consecration, designating something as an offering. And when his mouth and his heart are not in agreement, the matter does not take effect.
"She'eini nichnas l'vayis zeh v'amar la'zeh" - he swore that he would not enter a particular house, and he meant this house, but by mistake he said it about the other house. This is the third category, an oath.
"She'eini neheneh la'zeh v'amar la'zeh" - he intended to say that a particular item should be forever forbidden to him for benefit, and by mistake he named the other item: he meant to say "table" and said "chair," and the like. This is the fourth category, a vow.
"Lo amar klum, ad she'yihyu piv v'libo shavin" - in all four of these cases what came out of the person's mouth carries no halachic significance, and his words do not bind him unless his mouth, what he said, and his heart, what he intended, are equal and match one another.
To summarize: the four categories - Terumos and ma'asros, vows of consecration, oaths, and vows of prohibition - all share one guiding principle: a person must say what he means and mean what he says, and if not, his words do not bind him.