Chapter on Usury (Riba)
Man Lā Yaḥḍuruh al-Faqīh|Volume 3|Book 2|Chapter 27
وَ قَالَ عَلَيْهِ اَلسَّلاَمُ: "كُلُّ رِبًا أَكَلَهُ اَلنَّاسُ بِجَهَالَةٍ ثُمَّ تَابُوا فَإِنَّهُ يُقْبَلُ مِنْهُمْ إِذَا عُرِفَتْ مِنْهُمُ اَلتَّوْبَةُ " وَ قَالَ عَلَيْهِ اَلسَّلاَمُ "لَوْ أَنَّ رَجُلاً وَرِثَ مِنْ أَبِيهِ مَالاً وَ قَدْ عَلِمَ أَنَّ فِي ذَلِكَ اَلْمَالِ رِبًا وَ لَكِنْ قَدِ اِخْتَلَطَ فِي اَلتِّجَارَةِ بِغَيْرِهِ فَإِنَّهُ لَهُ حَلاَلٌ طَيِّبٌ فَلْيَأْكُلْهُ وَ إِنْ عَرَفَ مِنْهُ شَيْئاً مَعْزُولاً أَنَّهُ رِبًا فَلْيَأْخُذْ رَأْسَ مَالِهِ وَ لْيَرُدَّ اَلرِّبَا ".
Imam عليه السلام said: "Any usury that people consumed out of ignorance, and then they repented, it will be accepted from them once their repentance is recognized." And Imam عليه السلام said: "If a man inherits wealth from his father and knows that there is usury in that wealth, but it has been mixed with other lawful trade, then it is permissible and pure for him to consume it. However, if he identifies a specific portion as usury, he should take his principal amount and return the usury."
- Ṣaḥīḥ al-Faqīh