When a person enters into an agreement with another and raises specific conditions upon which the agreement is based, must we follow the specific statements that he makes, or should we accept his claim that his intent was something else? One example presented in the Gemara was the man who sold his possessions with the intent of moving to Israel. In the end, his aliyah was unsuccessful and he returned to his original home. Can he have the sale cancelled with the argument that he was not able to settle in Israel, or were the sales final?
This case – together with similar ones discussed in the Gemara – is a category referred to as devarim she-ba-lev – “thoughts in one’s heart” – and the question is whether they are to be taken seriously or not.
The question of devarim she-ba-lev applies not only to monetary matters, but to other areas of halakha, as well, and the rishonim and aharonim who discuss it bring many sources that do not appear in our Gemara. The apparent conclusion of our Gemara is that devarim she-ba-lev einam devarim – that we cannot consider unexpressed intentions, and Rabbeinu Tam objects to that ruling based on the laws of korbanot where we find that in a case where a person intends to declare a specific animal or object to be hekdesh, but inadvertently points to a different one, it is the intended one that becomes holy, not the one that was chosen accidentally. Rabbeinu Tam argues that this clearly shows that devarim she-ba-lev are taken into account by the halakha.
The Ramban responds by distinguishing between an accidental statement and a secret intent. The case where a person made a statement by accident would be considered an ones – something that happened that was beyond the person’s control – where we would not hold the person responsible. Nevertheless, a person cannot simply come and claim that he had a secret intent that must be taken into account after the fact.
Most of the rishonim accept the approach of Rabbenu Hananel who ruled that devarim she-ba-lev einam devarim, but that if circumstantial evidence points to the fact that the person meant to include a condition, it will be taken into account. Thus, for example, were someone to give away his estate, unaware that he would recover from his illness, we would recognize that his presents were made under mistaken assumptions and he could negate the gifts upon recovery.