Commentary for Bava Batra 270:11

Another question to Rav Meir (?) regarding Reuven who makes a claim against Shimon, saying that his mother left a security in the hands of Shimon, and when she handed over the security she told him to give it to Reuven her son upon her death. And Shimon replies that at the time of giving over the security she said that if she needs it I should return it to her, and if she dies that he should give it to Reuven her son. And the ruling was that Reuven did not acquire the gift, because given that the mother was healthy at the time, and she did not perform an act of acquisition on the gift, nor did Reuven, and a gift from a healthy person requires an act of acquisition. And even though in Baba Batra 135b: "Which deed of gift of a healthy person is considered like the deed of gift of a person on his deathbed, in that the recipient acquires it only after the death of the giver? Any deed in which it is written: From today and after my death." And Rabenu Tam comments that it is written, from today if I don't return, until after death, means that after death he acquires it even without an act. That case is different because it is written from today, according to Rav Yehuda, and according to Rav Yossi even if it is not written from today, because the date in the deed informs. But in our case, she did not say from today, and there is no deed nor act which supports the gifting, to tell us that it was gifted in her lifetime, therefore there is no acquisition, for there is no gifting after death from a healthy person. And also cannot say that he acquired it because there is a Mitzvah to uphold the wishes of the dead, because it was not placed in escrow from the beginning. ...