Nedarim 43b — the Talmud in English

But if he declared it ownerless before his vow -

it is permitted.

And if you say that the matter does not leave the authority of the one who declared it ownerless

until it comes into the authority of one who acquires it,

then,

what difference is there whether he made his vow before declaring it ownerless, or whether he declared it ownerless before making his vow,

ultimately, the one forbidden by vow to derive benefit acquires it from the authority of the one who forbade it to himself!?

He raises the objection, and he answers it:

In truth, if the one who declared it ownerless wishes to retract, he can do so as long as another has not acquired it. Nevertheless, if his declaring it ownerless preceded his vow, the one forbidden by vow to derive benefit is permitted to benefit from it, because

everyone who vows -

does not have in mind what he declared ownerless.

Consequently, he did not forbid this object to him at all, even though it is still considered to be under his authority.

Rava raises an objection:

A dying person who had two slaves, and gave

some

of his property

to

to a

first slave, and

afterward gave

all

all his property

to the second,

and afterward that man recovered from his illness, then the

first slave acquired what his master transferred to him, and his master cannot retract, because a gift of part [of the property] does not have the status of a gift of a dying person, who can retract if he recovers from his illness. But the

what his master had given him, and his master cannot retract it, because a gift of part of one’s property is not subject to the law of the gift of a seriously ill person, who can retract it if he recovers from his illness. But the

second did not acquire,

in accordance with the law of a gift of a dying person who gave all his property, who can retract if he recovers.

And now, one is forced to say that when he gave to the second, he intended to give him also what he had already given to the first. For if not, but he intended to give him only what remained after what he had given to the first, then he divided all his property, and this entire gift has the status of a gift of a dying person. Why, then, did the first acquire?

Rather, one is forced to say that he gave the second also what he had already given the first. We see that his mind is on what he gave; and the same applies to our matter, that his mind is on what he declared ownerless!

Rather, Rava said: This is the reason of Rabbi Yosei: a decree on account of the gift of Beit Horon

the incident brought below in the Mishna. Since we are certain that he declared it ownerless only so that the one forbidden by vow to derive benefit would acquire it, we are concerned that if we permit this to be done, people will come to permit it even in a case where the one who forbade it explicitly said that he was declaring it ownerless so that the one forbidden by vow to derive benefit would acquire it, as in the gift of Beit Horon.

It was taught: One who declares his field ownerless, for all three days -

can retract

even if another has already acquired the field. And the reason is that they instituted a measure because of the deceivers: since ownerless property is exempt from the tithe, they would declare their fields ownerless in order to become exempt, and their intention was to return and acquire them. It follows that their declaring them ownerless was only for deception. Therefore they instituted that this should not be ownerless property at all, and even if another acquired them, the owners can retract.

From here onward,

after three days -

the one who

declared it ownerless

cannot retract.

For after three days have passed, we are no longer concerned about deceivers. For if he truly intended only to exempt himself from the tithe, he would not have waited to retract until after three days! Rather, certainly he intended a complete declaration of ownerlessness.