by taking it out of the building, the person is taking advantage of someone's goodwill.

Dear Sam,
That was an excellent way of phrasing why it would be forbidden.
Take care.
Rabbi Flom

Thank you Rabbi Flom.

Dear Sam,
I know that it is a year and a half since this was written, but...
Something happened recently, that relates to "the person is taking advantage of someone's goodwill". Avraham asked Yitzchok for a favor, and it was CLEARLY something that Yitzchok did NOT want to do, but said he would because he is a gutta neshama (kind hearted). I told Avraham that Yitzchok really didn't want to do it. Avraham said "I know, but it's his tough luck, because he told me he'd do it." I have a mussar talk about even if people volunteer to do something, you don't always have the right to accept. Certainly to actively persuade someone to give you something that they don't want, is forbidden.
Thanks.
Rabbi Flom

If Yitzchok offers something to Avraham and Avraham accepts, regardless of whether Avraham thinks Yitzchok really wanted the offer accepted, is this a binding committment on Yitzchok that if he wants out he has to request a release?

And if Avraham doesn't want to release Yitzchok, that Yitzchok can go to a Beis Din for a procedure similar to being released from a vow?

Also...

I understand that in secular law there is a difference between a unilateral contract and a bilateral contract...

Is there any halachic difference in whether Yitzchok was receiving something in return (either from Avraham or from a 3rd party) as to whether Yitzchok was obligated to do that which Avraham accepted?

Dear Rob,
Thanks for the question.
If I say I am going to do something but there is no kinyan, transaction, it is not legally binding. I might have to worry about a neder,vow, but I think that that problem is unaffected by whether or not you want to release me.
Take care.
Rabbi Flom

Interestingly learning in commentary of the Rosh on the first mishna in Bava Basra today, and we were discussing the case of two partners dividing a commonly owned courtyard, and rather than requiring each other to build a privacy wall, each forgave the damage to the other of not having the privacy wall.

If either of them change their mind and do want the wall, since they were released from having to pay for their half of the wall, this is not the type of situation which can be unilaterally released.

I take from this that there is a recognized difference between unilateral and bilateral benefit.

Is this however a case of a binding obligation without a kinyan?