Harmful effects of Riba
Question

                Assalamu alaikum
      Why is Riba (Usury) forbidden? I need a convincing answer to give it to some of my
      brothers in town.Jazakum allah alf Khair
Praise be to Allah.Wa ‘alaykum al-salaam wa rahmat-Allaahi wa barakaatuhu.
Riba is forbidden because of the harmful effects that result from it,
    such as:
    Economic effects, e.g., keeping money idle and unproductive, and swelling the ranks of the
    poor;
    Social effects, e.g., cutting ties, creating enmity and hatred between the poor and the
    rich, and spreading corruption and promiscuity caused by need;
    Psychological and spiritual effects, e.g., arrogance, looking down on others,
    hard-heartedness and exploiting the needs of the poor.
    The above describes the effects of Riba on the individual level. On the state level,
    countries are weakened, their resources fall under the control of others, they end up
    following their enemies’ desires, they are robbed of their natural wealth and their
    problems get even worse. This is what we see happening in reality. We ask Allaah to keep
    us safe and sound..