דברים, פרק כ״ג, פסוק כ״א

A clear distinction is drawn between standard commercial practices and the duty of internal brotherhood within a nation. The economic system is designed to operate on two different planes: externally, it follows natural economic laws, while internally, it is built upon a foundation of kindness and mutual aid. The primary approach among commentators is that lending and borrowing with interest is generally permitted in foreign commerce [שטיינזלץ, בכור שור]. However, some view the instruction regarding foreigners as an absolute positive commandment to charge them interest [חזקוני, תורה תמימה, רבנו בחיי בשם הרמב״ם], with one perspective suggesting this serves to diminish the financial resources of idolaters [רלב״ג]. Others view this not as an obligation but as a permission, based on the understanding that charging interest is not inherently unjust. Rather, it is a standard, logical business practice where a person earns a return on their capital [רבנו בחיי, ביאור יש״ר]. Since foreigners typically did not own land in Israel and borrowed money primarily for commercial ventures, it was entirely natural to claim a share of their profits [העמק דבר, שד״ל]. Furthermore, because other nations charge interest to Israelites, basic justice dictates a reciprocal arrangement. This dynamic is comparable to a group of merchants who agree to favorable, interest-free terms among themselves while operating for profit in the broader market [תורה תמימה, מלבי״ם]. A unique approach even frames the dynamic with foreigners as a moral obligation: if a Jew borrows from a foreigner and agrees to pay interest, he must honor his word to prevent betrayal and avoid desecrating God's name [ספורנו, הכתב והקבלה, מלבי״ם].

In stark contrast, charging interest to a fellow Jew is absolutely prohibited, even if the borrower willingly consents and wishes to pay [ספורנו]. This strict ban stems from the principle that internal loans are not meant to be commercial enterprises. Instead, they are intended as acts of charity, kindness, and fraternal support for the impoverished [שד״ל, ביאור יש״ר]. The severity of this prohibition is underscored by the understanding that a lender who charges a fellow Jew interest violates multiple prohibitions, such as placing a stumbling block before the blind, and nullifies the positive commandment derived from the allowance to charge interest exclusively to foreigners [רש״י, מזרחי, גור אריה, שפתי חכמים, אור החיים]. Interestingly, some interpret the directive as a warning directed specifically at the borrower, cautioning him not to pay interest and thereby cause the lender to commit a financial offense against him [מלבי״ם, הכתב והקבלה]. To protect the integrity of this internal system, the Sages restricted the allowance of lending to foreigners with interest, permitting it only to secure basic living necessities. This limitation was enacted out of concern that extensive financial dealings might lead a person to adopt foreign business practices and eventually charge interest to fellow Jews, an exception being made only for Torah scholars whose ethical grounding is secure [רבנו בחיי, בכור שור, אור החיים].

A profound reward is promised for adhering to this standard of financial brotherhood. The Divine blessing on all of a person's endeavors is granted precisely because offering an interest-free loan requires a genuine financial concession and an act of pure kindness. Heavenly blessing rests upon acts of charity, rather than on exploitation or deceit [הטור הארוך]. When a person conducts business with a spirit of brotherhood and reverence for God, their earthly actions draw down a heavenly reward [רש״ר הירש, מלבי״ם]. Although the prohibition against charging interest applies universally, the Land of Israel is specifically highlighted because it is uniquely attuned to Divine providence. It is the place where this spiritual blessing becomes most visibly manifest [רלב״ג, הכתב והקבלה, ביאור יש״ר, העמק דבר]. Alternatively, the very inheritance of the land is viewed not as an unconditional gift, but as a direct reward for the faith in God that is demonstrated when one willingly sacrifices the guaranteed profits of interest [מלבי״ם].