Our Gemara relates that Rava received the following question about a neder, from Rav Hiyya bar Avin:
What is the law if a person says to his friend, “I forbid you from deriving any benefit from my loaf of bread,” and then gives him that loaf as a present? Should we assume that the person who took the vow only meant to forbid the loaf of bread while it was his, and when he transferred it into his friend’s possession, the effect of the vow was over, or should we say that the neder remains in effect throughout?
Rava responds that it is obvious to him that the loaf of bread remains forbidden.
Several of the commentaries raise an obvious question. By definition, forbidding someone to benefit from an object that belongs to you should prohibit transferring ownership of the object to that person, since by taking possession of it he is clearly deriving benefit from it. In his Keren Ora, Rabbi Yitzhak mi-Karlin explains that the simple interpretation of forbidding benefit from a loaf of bread is that it becomes prohibited to eat. Therefore the Gemara takes for granted that the loaf can be given as a present to the person about whom the neder was made. The discussion in the Gemara is whether the prohibition against eating the loaf remains in force even after the bread has been transferred out of the possession of the person who took the neder and into the possession of the person about whom the neder was made.
Rabbi Avraham min HaHar suggests that the continuation of the Gemara effectively deals with this question. The Gemara raises the question of whether the loaf of bread would remain forbidden if it had been stolen by another and was no longer in the possession of the original owner – the implication being that if such a transfer of ownership would effectively permit the loaf, perhaps receiving it as a present would accomplish that, as well.