http://revach.net/article.php?id=223

Section: Parshas HaShavua   Category: Quick Vort
Parshas Behar: Shela HaKadosh and Rav Chaim Kanievsky Do We Fight With Our Brother or Do We Steal From Him

 The Passuk in Parshas Behar mentions twice the issur of " Lo Soinoo" ("One shall not harass another Jew") The Shelah Hakodesh asks, why concerning the first Lav does the Torah say, " Lo Soinoo Ish Es Achiv " - one should not harrass his brother, but concerning the second Lav the Torah says, " Lo Soinoo Ish Es Amiso " - one should not harrass his friend"?

The Shela answers, the second Lav of "Lo Soinoo" is referring to verbal harrassment (as Rashi explains), since one does not typically harrass his brother verbally, therefore the Torah says , Ish Es Amiso  - one should not harrass his friend . The First Lav, Rashi explains, is referring to cheating another Jew monetarily. Since it is common for one to cheat even his brother, therefore the Torah states by that Lav "Lo Soinoo Ish Es Achiv " - one should not harrass his brother ! 

Rav Chaim Kanievsky offers the opposite logic.  When it comes to a brother it is impossible to refrain from verbally fighting with him.  Therefore the pasuk requires us only V'Ahavta "L'Rei'acha, you must love your friend.  The obligation towards you brother is only not to hate him in your heart (Lo Sisna Es Achicha Bilvavecha).  But when it comes to money you are equally responsible not to cheat your brother or your friend.