Is it permissible to compensate for usurious interest that the deceased father used to spend, with sums collected from a lawful income equal to that interest?

It is not permissible to deposit money in savings accounts in usurious banks, and one must repent from having done so. As for the usurious interest that a person has spent, he is not obligated to do anything concerning it other than repenting. However, whatever remains of it, he is obligated to dispose of by giving it to the poor and the needy, unless he was ignorant of its prohibition or followed someone who issued a fatwa permitting it. If the owner of ill-gotten wealth dies, it becomes permissible for his heir. The children are not obligated to donate an amount equal to the usurious interest their father spent. However, if they do so as charity on his behalf, it will benefit him, and it is hoped that Allah will expiate his sin of consuming ill-gotten gain. It is recommended that the charity be Sadaqah Jariyah (ongoing charity), along with frequent supplication and seeking forgiveness for him.