How can money be purified from the effect of usurious interest after repaying the related loans and purchasing various properties?

Usury is one of the gravest major sins. Allah has warned its perpetrator with eradication, loss of blessings, and war from Allah and His Messenger, as stated in His Almighty قول: (But if you do not, then be informed of a war [against you] from Allah and His Messenger. But if you repent, you may have your principal – [thus] you do no wrong, nor are you wronged).

Repentance from usury is achieved through remorse, a firm resolve not to return to it, and increasing supplications for forgiveness and good deeds. Allah the Almighty said: (Except for those who repent, believe and do righteous work. For them Allah will replace their evil deeds with good ones. And ever is Allah Forgiving and Merciful).

If a servant repents with sincere repentance, we hope for their forgiveness. If they can repay the principal debt without the usurious interest, they should do so. Otherwise, there is no blame upon them for repaying the full amount if they are compelled to do so. As for what they consumed from usurious loans, there is no harm in benefiting from it, because the prohibition relates to their accountability, not to the money itself.