THE BLINDNESS OF THOSE THAT CHARGE INTEREST
What is the meaning of the term 'Yored Imo L'Chayav'?
Rashi: He often quarrels with him as if he hit him and is coming to kill him.
Tosfos: The Teshuvos ha'Geonim bring from Rav Tzadok Gaon that he is permitted to burn one third of the person's produce.
Maharsha: If the person is a craftsman with a store, he may open a store next to him.
Ben Yehoyada: The Pasuk in Shir ha'Shirim states "His cheeks (L'Chayav) are like a bed of spice". Chazal compare the spice bed to the different aspects of Torah. Thus, the cheeks are the place of Torah. It is known that when one gives a bad name for his friend, he gives over his merits to him. This is the meaning of 'Yored Imo L'Chayav' - he will also take from him the Torah that is in his cheeks.
How did he 'deny Elokei Yisrael'?
Ben Yehoyada: Chazal say that the Name 'Elokei Yisrael' connotes Hash-m's supervision over this world. One who charges interest does not trust in Hash-m and his actions show that he denies Hash-m's Divine supervision.
Maharal: Jews are brothers, who have a Father who sustains them, giving them life. When someone charges another Jew interest, he is taking from him that which sustains him, thereby denying that it is Hash-m who sends them the sustenance.
ONE WHO LENDS WITHOUT CHARGING INTEREST
Do we not find that those who do not lend on interest sometimes fall?
Shev Shmaatsa (Intro): One who lends in interest - his assets will collapse and will not go to anyone. One who does not, even if his assets collapse, they will go to others. This also explains the Midrash Eicha - on the Pasuk (Yechezkel 7:19), "They will cast their silver in the streets and their gold will be repugnant" - this refers to the silver of those who lend on interest.