ויקרא, פרק כ״ה, פסוק ל״ו

The prohibition against lending with interest transcends basic economic policy, serving as a profound test of morality and faith. It directly challenges the natural human instinct to generate guaranteed profit from capital, demanding instead a society built on mutual responsibility and the recognition that all wealth ultimately belongs to God. This standard of care applies to any brother, encompassing both native Israelites and righteous converts [רלב״ג]. The restriction is absolute: a lender may not accept any addition to the principal, even if the borrower offers it willingly out of gratitude [ביאור יש״ר, הופמן]. Furthermore, one cannot bypass this law through legal loopholes, such as using a non-Jewish guarantor or intermediary [מלבי״ם, אדרת אליהו].

Biblical law addresses interest through two distinct concepts. The primary approach among commentators is that these describe the same fundamental act, presented dually so that a transgressor violates two separate prohibitions [רש״י, מזרחי, מלבי״ם]. This duality emphasizes two facets of the sin: the direct harm inflicted upon the borrower, and the unlawful accumulation of wealth [גור אריה]. However, a closer reading reveals a conceptual distinction. One form of interest is rooted in the imagery of a bite, describing debt that accumulates over time. Much like snake venom that enters through a minor scratch and spreads throughout the body, this highlights the expanding damage and direct loss suffered by the borrower [רמב״ן, כלי יקר, רש״ר הירש, שטיינזלץ]. The other form focuses on the lender's perspective, denoting a pre-arranged addition paid at the end of the loan period. This simply increases the lender's wealth, sometimes even without causing direct financial loss to the borrower, such as in cases involving market fluctuations [רמב״ן, שטיינזלץ, רש״ר הירש, ביאור יש״ר].

Theologically, charging interest damages a person's trust in God. While a merchant relies on Divine providence for business success, a lender charging interest secures a fixed, guaranteed profit, effectively removing himself from God's oversight [כלי יקר]. Since all money belongs to God, extracting profit without sharing in the borrower's effort or risk directly contradicts the Divine will [רש״ר הירש, חומש קה״ת]. Because human logic easily justifies interest, people might rationalize the practice by arguing that their idle funds could have earned profit elsewhere, or that the borrower is also benefiting from the loan [רש״י, ביאור יש״ר, רש״ר הירש]. Therefore, the commandment is coupled with a demand to fear God. This serves as a warning against masking illicit actions, such as funneling money through a non-Jew to lend to an Israelite. Since these deceptive practices are matters of the heart and difficult to prove publicly, the reminder stands that God sees all hidden intentions [רש״י, ברטנורא, צאינה וראינה].

Ultimately, the purpose of this law is to ensure that a destitute brother can survive with dignity rather than face financial ruin. Extracting interest drains the borrower's vitality, making it akin to taking his very life [ספורנו, כלי יקר, העמק דבר]. For this reason, a rabbinic court will force a lender to return unlawfully collected interest in order to restore the borrower's livelihood [מלבי״ם, אדרת אליהו]. Yet, the requirement that the brother live alongside the lender establishes a clear boundary on self-sacrifice. One is commanded to lend and assist, but only if it does not jeopardize their own financial survival. A person's own life takes precedence; the brother must be supported to live alongside them, but not at the cost of their own existence [ספורנו, רלב״ג, מלבי״ם, אדרת אליהו]. Finally, this directive carries an eternal promise: those who refrain from taking interest and actively care for their brother's livelihood in this world will merit to live together in the future resurrection of the dead [פרדס יוסף].