Responsa for Nedarim 89:1
איבעית אימא הא דאפקריה באנפי תרין והא דאפקריה באפי תלתא דאמר ר' יוחנן משום רבי שמעון בן יהוצדק כל המפקיר בפני שלשה הוי הפקר בפני שנים לא הוי הפקר
Alternatively: One case refers to hefker declared in the presence of two; the other, if declared before three. For R. Johanan said in the name of R. Simeon b. Jehozadak: Hefker declared in the presence of three is valid, but not in the presence of two.<span class="x" onmousemove="('comment',' Until one actually takes possession. Therefore, in the Mishnah, since no person is present, R. Jose maintains that if the maddir declares the food hefker, and the muddar takes it, he receives it directly from the maddir. But the vineyard, we assume, was renounced in the presence of three; therefore even R. Jose agrees that the renunciation is immediately valid. Hence, if he re-acquires it, it is exempt from tithe. The stronger validity of hefker in the presence of three is due to its greater publicity. ');"><sup>1</sup></span>
Teshuvot Maharam
A. A gave the valuables to C in order that he deliver them to B should a certain condition not be fulfilled. Such a transaction is called asmakhta and is not binding since it was not made before an authoritative court. When A finally told C to deliver the valuables to B, he was acting under misapprehension that they were due him legally, as his statement indicates. His order, therefore, was not binding and B should return the valuables to A.
SOURCES: Cr. 290; L. 309; Mord. B. B. 324; Tesh. Maim to Kinyan, 3.