Halakhah for Bava Batra 10:5
מִי שֶׁפָּרַע מִקְצָת חוֹבוֹ וְהִשְׁלִישׁ אֶת שְׁטָרוֹ וְאָמַר לוֹ, אִם לֹא נָתַתִּי לְךָ מִכָּאן וְעַד יוֹם פְּלוֹנִי תֶּן לוֹ שְׁטָרוֹ, הִגִּיעַ זְמַן וְלֹא נָתַן, רַבִּי יוֹסֵי אוֹמֵר, יִתֵּן. רַבִּי יְהוּדָה אוֹמֵר, לֹא יִתֵּן:
If one paid part of his debt and gave his bill (of indebtedness) to a third person [i.e., If the lender and the borrower gave the bill to a third person on whom they relied, it being bothersome to them to write a receipt], and he (the borrower) said to him (the third person): "If I have not given you (the balance) from now until this and this day, give him (the lender) his receipt" — If the time arrived and he did not give it, R. Yossi says: He should give it (the bill, to the lender). R. Yehudah says: He should not give it. [R. Yossi holds that asmachta effects acquisition, viz.: If one promises his neighbor something on condition that he do something for him in the future, and he is confident ("somech") in his heart at the time of the condition that it can be fulfilled, and when the time arrived, it could not be fulfilled, this is called "asmachta," and, according to R. Yossi, it effects acquisition. As to the halachah, asmachta does not effect acquisition, unless they acquired (authority) from his hand in a distinctive beth-din, and he relegated his rights to that beth-din, assigning it his bills and certifications and said: "If I do not come from now until thirty days, let my rights be annulled." My teachers explain that every expert beth-din, which is acquainted with the laws of asmachta is regarded as a "distinctive" beth-din in this regard; but Rambam says that only a beth-din ordained in Eretz Yisrael qualifies as "distinctive."]