Rambam - Sefer HaMitzvos: Negative Mitzvah 237: Negative Mitzvah 237

Negative Mitzvah 237: It is forbidden to participate in a loan in which interest is charged
Exodus 22:24 "Neither shall you take interest from him"

This Negative Mitzvah cautions us not to take part in any deal or loan that involves interest.

For example: We may not serve as guarantor (person responsible if the borrower doesn't pay) or a witness in such a deal.

Nor may we provide our services to write up the contract between the borrower and lender.

I don't believe in philosophy. I believe in ideas that change people.

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The Rebbe initiated a campaign to turn Jewish people back to traditional Jewish practice. The entire campaign was focussed on getting people to do things, such as lighting a candle on Friday before sunset, putting a few pennies in a charity box every day, wearing tefillin every morning, etc.. The Rebbe emphasized again and again: Don't get into debate, don't get lost in philosophy. Just get people to do, and talk about it later.
Many criticized the campaign for this emphasis on action. "People need to understand what they are doing, or else it is empty ritual," they argued.
The Rebbe replied: People are not changed by arguments, nor by philosophy. People are changed by doing. Introduce a new habit into your life, and your entire perspective of the world changes.
First do, then learn about what you are already doing.

From: Bringing Heaven Down to Earth by Tzvi Freeman - tzvif@aol.com