Qitzur Shulchan Arukh – 65:1
סִימָן סה – הִלְכוֹת רִבִּית
Chapter 65: Laws of Interest
A person’s soul naturally longs for and desires money, and it is more likely that a person will fail in the prohibition of interest than other monetary prohibitions, for theft, deceit, etc… a person can watch himself that he doesn’t steal or deceive his fellowman. At times he is stopped by embarrassment or fear/awe [from violating those other prohibitions]. Which isn’t true for interest, because the borrower gives it to him in goof will, and he is happy because he found a way to borrow the money even if with interest. And also the lender thinks in his mind that he did a great favor for the borrower who can now gain through this money multiples upon multiples more than the interest. Therefore, it is very easy that a person would (G-d forbid) be tempted by the yeitzer hara to fail in this prohibition.
Therefore, our holy Torah was very strict about this prohibition, and many specific prohibitions were declared about it. The lender violates 6 prohibitions and will not arise during the resurrection of the dead, as it says (Yechezqeil 18:13), “”He gave [money] at interest and took an increase – shall he live? He shall not live.” The borrower violates three prohibitions. The scribe [who wrote up the contract], the witnesses and the cosigner each violate one prohibition. So too the broker who dealt between them, or who recommended the deal to one of them, such as if he shows the borrower where to find the loan or the lender where to lend his money, he also violated one prohibition.
A thought about interest. If the problem were general moral grounds, then the prohibition would not be limited to charging Jews interest. As we saw with the laws of speech, which included all people, or those of correcting someone else’s financial mistakes, which included all non-idolaters. After all, as we see in our text, borrowing with money is often a win-win situation. If both sides gain, how can the problem be fiscal ethics?
The text of the verse is “וְכִֽי־יָמ֣וּךְ אָחִ֔יךָ וּמָ֥טָה יָד֖וֹ עִמָּ֑ךְ … אַל־תִּקַּ֤ח מֵֽאִתּוֹ֙ נֶ֣שֶׁךְ וְתַרְבִּ֔ית… — when your brother becomes poor, and his means fail from among you … do not take from him interest or increase…” (Vayiqra 25:35-26) The source of the prohibition appears to be that brothers don’t charge each other interest. The immorality is in the lack of Jewish unity implied, not in the interest itself.
This appears to be the Qitzur’s explanation why lending with interest has up to 6 specific violations involved. Because it lacks the basic moral imperative not to take advantage of others, people lack the natural reluctance or embarassment that keeps us from most fiscal wrongs. Therefore, Hashem provided more explicit exhortations in the Torah.
This lack of it actually being a moral issue also goes some of the way to explaining our willingness to engineer a heter iska, a contract that gains many of the advantages of an interest-bearing loan, but without the prohibitions. But that will wait for next chapter.