Rambam - Sefer HaMitzvos: Negative Mitzvah 250: Negative Mitzvah 250

Negative Mitzvah 250: It is forbidden to cheat in business deals
Leviticus 25:14 "You shall not defraud one another"

We are forbidden to deceive or cheat another person when conducting business with him.

Even if all your complaints about your spouse are well founded and valid -- show her your love, nevertheless. Show her unconditional love. It is said that all our exile is due to the sin of unmitigated hatred. When each one of us will start with unmitigated love in our own domain, from there it will spread to all else that we do, and from there to the entire world, speedily in our days, amen.

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