Jerusalem Talmud Bava Metzia 5:7

משנה: לֹא יֹאמַר אָדָם לַחֲבֵירוֹ הַלְװֵנִי כוֹר חִיטִּין וַאֲנִי אֶתֶּן לָךְ מִן הַגּוֹרֶן. אֲבָל אוֹמֵר לוֹ הַלְוֵנִי עַד שֶׁיָּבֹא בְנִי אוֹ עַד שֶׁאֶמְצָא הַמַּפְתֵּחַ. וְהִילֵּל אוֹסֵר. וְכָךְ הָיָה הִלֵּל אוֹמֵר לֹא תַלְוֶה אִשָּׁה כִּכָּר לַחֲבֵירָתָהּ עַד שֶׁתַּעֲשֶׂנּוּהָ בְדָמִים שֶׁמָּא יוֹקִירוּ הַחִטִּים וְנִמְצְא בָאוֹת לִידֵי רִבִּית. MISHNAH: A person may not say to another, lend me a kor of wheat and I shall return it to you from the threshing-floor¹⁸⁰This is the general prohibition of lending commodities against the same amount of commodities since lending and repayment might represent very different values on the spot market., but he may tell him, lend me until my son comes or until I find the key¹⁸¹Short term loans for which no big change in commodity prices is to be expected., but Hillel forbids. Similarly, Hillel¹⁸²While the records of Hillel’s time, the reigns of Caesar and Augustus, do not indicate inflationary pressures, it is possible that in Egypt and the neighboring countries the price of wheat was very sensitive to the requisitions for the provision of Rome and therefore unpredictable. said that a woman may not lend a loaf to another unless she fixed its price, for possibly wheat may rise in price and they would be entangled in problems of interest.

הלכה: לֹא יֹאמַר אָדָם לַחֲבֵירוֹ כול׳. תַּנֵּי. לֹא יֹאמַר אָדָם לַחֲבֵירוֹ. הַלְוֵינִי כוֹר חִטִּים וַאֲנִי נוֹתֵן לָךְ לַגּוֹרֶן. הָא עַד שְׁתַּיִם שָׁלֹשׁ שַׁבָּתוֹת מוּתָּר. וְהִלֵּל אוֹסֵר. שְׁמוּאֵל אָמַר. הֲלָכָה כְּהִלֵּל. HALAKHAH: “A person may not say to another,” etc. It was stated: “A person may not say to another, lend me a kor of wheat and I shall return it to you from the threshing-floor,” therefore for two or three weeks it is permitted; “but Hillel forbids.¹⁸⁵E adds: “But he may tell him, lend me until my son comes or until I find the key, but Hillel forbids;” therefore two or three weeks is forbidden. The formulation of L shows that his short text is original; the implication of both texts is the same.” Samuel said, practice follows Hillel¹⁸⁶Babli 75a; the editors of the Babli reject Samuel’s statement..