سورة البقرة

Imam Sadiq (peace be upon him): Ubayd ibn Zurara said: I said to Imam Sadiq (peace be upon him): "Explain the major sins to me." The Imam said: "The major sins are five, which necessitate entering the Fire: ... [one of them is usury.] Allah says: یا أَیُّهَا الَّذِینَ آمَنُوا اتَّقُوا اللهَ وَ ذَرُوا ما بَقِیَ مِنَ الرِّبا [O you who believe! Fear Allah and give up what remains of usury]."

Imam Rida (peace be upon him): یا أَیُّهَا الَّذِینَ آمَنُوا اتَّقُوا اللهَ وَ ذَرُوا ما بَقِیَ مِنَ الرِّبا [O you who believe! Fear Allah and give up what remains of usury] ... means that he must give up the profit which he has gained from the principal capital [as usury]; even the flesh of his body which has come into being from consuming usury — after repenting he must shed it, in this way that [for example] every day he goes to the bath on an empty stomach [so that the flesh of his body melts away]. This [ruling relates to] when he repents from consuming usury, taking it, and dealing in it.

Ali ibn Ibrahim (may Allah have mercy on him): The reason for the revelation of this verse is that when Allah revealed the verse: الَّذِینَ یأْکلُونَ الرِّبَا [Those who consume usury] ..., Khalid ibn Walid went to the Messenger of Allah (peace be upon him and his family) and said: "O Messenger of Allah (peace be upon him and his family)! My father has some wealth with Thaqif (the name of a tribe) which he obtained through usury, and at the time of his death he willed me to collect it." For this reason, Allah the Blessed and Exalted revealed the verse: یا أَیها الَّذِینَ آمَنُواْ اتَّقُواْ اللّه وَذَرُواْ مَا بَقِی مِنَ الرِّبَا إِن کنتُم مُّؤْمِنِینَ [O you who believe! Fear Allah and give up what remains of usury if you are believers].

Imam Baqir (peace be upon him): If you know that wealth relates to a usurious transaction, then separate your [original] capital from it and return the rest to its owner.

Imam Sadiq (peace be upon him): If someone inherits wealth from his father and realises that within that wealth there is riba (usury), but during trade it has become mixed with other wealth, it will be lawful and wholesome for him. So he may consume it and use that money; and if he realises that a portion, set apart from the other wealth [and clearly identified], comes from riba, he must take out his original capital from it and return the rest [to its owners].