Responsa for Bava Batra 294:1
לתפלתו של כהן גדול
— In respect of the prayer of the High Priest [on the Day of Atonement]<span class="x" onmousemove="('comment',' When he offered up a special prayer for rain. If the signs indicated heavy rains. his prayer had to be modified. ');"><sup>1</sup></span> Raba,<span class="x" onmousemove="('comment',' At this point is resumed the discussion of the theme introduced by R. Zera (p. 634). ');"><sup>2</sup></span> however, said in the name of R. Nahman: The [validity of a verbal] gift of a dying man is a mere [provision] of the Rabbis<span class="x" onmousemove="('comment',' Biblically the gift would not be valid unless attended by actual or symbolic acquisition. ');"><sup>3</sup></span> lest his mind become affected.<span class="x" onmousemove="('comment',' As a result of any resistance which might be offered to his instructions. Hence, legal force was given to his verbal and informal instructions as if legal acquisition had taken place. ');"><sup>4</sup></span>
Teshuvot Maharam
A. A dowry gift becomes the property of the donee only if the marriage takes place. Therefore, neither A nor his daughter has ever gained title to B's money, and A must return the principal plus the interest to B. Even if B expressly stipulated that he will forfeit the 15 pounds if the marriage does not take place, such a stipulation is considered an Asmakhta and is not valid. B, however, must pay A for his trouble in managing B's investments.
SOURCES: Cr. 86; Pr. 285; Mord. B.B. 615; Agudah B.B. 198.