hadith
4366
۞
Imam al-Sadiq (AS), when asked by Hisham b. al-Hakam about the reason behind the prohibition of usury, replied, 'Were usury to be permissible, people would abandon their trading and other necessities, so Allah prohibited usury in order that man may flee from the unlawful [means of earning] to trade, and resort to buying and selling, and this in turn facilitates borrowing from each other.
الإمامُ الصّادقُ (عَلَيهِ الّسَلامُ) ـ لَمّا
سَألَهُ هِشامُ بنُ الحَكَمِ عن عِلَّةِ تَحريمِ الرِّبا ـ: إنّهُ لَو كانَ الرِّبا حلالاً لَتَرَكَ الناسُ التِّجاراتِ وما يَحتاجونَ إلَيهِ فحَرَّمَ اللّهُ الرِّبا لتَفِرَّ الناسُ عنِ الحرامِ إلى التِّجاراتِ وإلى البَيعِ والشِّراءِ فَيَتَّصِلَ ذلكَ بَينَهُم في القَرضِ .