In the previous Halacha, we have explained in general the law that one may not loan or borrow money on interest.
One Se’ah for Another
Our Sages enacted that one may not borrow a Se’ah (a halachic measure of weight) of wheat from a friend with the intention of returning another Se’ah of wheat at a later time, for the Sages were concerned that the price of wheat may rise in the interim and that would mean that the borrower would be repaying more than he borrowed, thus causing both lender and borrower to transgress the prohibition of loaning on interest (on a rabbinic level). For instance, if one lends a friends ten pounds of flour with the understanding that the borrower will return it in a week’s time, this constitutes the rabbinic prohibition of “one Se’ah for another” since it is possible that at the time of the loan, the price of flour was ten dollars and at the time the borrower returns it, the price may jump to twenty dollars. The Sages therefore forbade this.
Assigning Monetary Value
There is, nevertheless, a permissible solution for lending food by weight which is that the borrower stipulates at the time of the loan that the he will repay the lender later with flour worth the same amount as the amount of flour he is lending him now. For instance, using the above example, if ten pounds of flour were valued at ten dollars at the time of the loan, the borrower should tell the lender, “When I return the flour, I will return an amount of flour worth ten dollars.” Thus, if the price of ten pounds of flour has risen by to twenty dollars by the time the borrower wishes to return it, the borrower will return only five pounds of flour valued at ten dollars, which was the monetary of the flour he borrowed at the time of the loan.
The Poskim refer to this idea as “assigning monetary value to the borrowed object” in which case it will be permissible to lend “one Se’ah” of wheat or flour for another.
Lending a Loaf of Bread
Based on the above, it would seem forbidden for a woman to borrow a loaf of bread from a neighbor with the intention of returning another loaf of bread at a later time since there is concern that the price of bread may rise in the interim, thus causing both parties to transgress the prohibition of loaning on interest. Nevertheless, the Rama writes that the custom is to rule leniently in this regard since people are not usually so particular regarding such small amounts of money (like the inflation of the price of a loaf of bread) and our Sages were likewise not so particular to rule stringently on a matter that is rabbinic in nature to begin with.
Thus, according to the Rama, when discussing amounts of money which are not so significant, there is room for leniency. It is therefore permissible to lend a loaf of bread or a bottle of milk and the like.
On the other hand, Maran Ha’Bet Yosef writes that according to the Rif and Rambam, the prohibition of “one Se’ah for another” applies even with regards to paltry sums since people are particular about any sum of money. Thus, the prohibition of “one Se’ah for another” would apply even to something small like a loaf of bread.
Accordingly, according to Maran Ha’Bet Yosef, whose rulings we have accepted, it would be forbidden to borrow or lend a loaf of bread or a bottle of milk.
Maran Rabbeinu Ovadia Yosef zt”l discusses this opinion of Maran Ha’Bet Yosef and quotes the words of the Shulchan Gavoha (authored by Hagaon Rabbeinu Yosef Molcho zt”l) who writes that even according to the Rif and Rambam that lending even something small is forbidden, this applies only in a place where people are particular about the inflation of the price of bread. However, in our times most people are not so particular about this. This is especially true since nowadays, thank G-d, there is much abundance in the world and as a result, even people who are not necessarily wealthy are not particular about the difference in the price of bread during the span of several days. Thus, the prohibition of loaning on interest does not apply here.
Thus, even according to Maran Ha’Bet Yosef, a woman may borrow a loaf of bread and the like from her neighbor with the intention of returning another one at a later time.
Nonetheless, this applies only to something small; regarding a large amount of merchandise, however, this is certainly forbidden, similar to the law of “one Se’ah of wheat for another.”