What is the ruling on paying off a father's debt with usurious money or with Zakat money?

There is no objection to paying the father's debt from zakat (definition) if the debt was incurred by him not in an act of disobedience, or if it was due to an act of disobedience and he repented sincerely. For one who is in debt is considered among the ghārimīn (those in debt). Similarly, there is no objection to paying the father's debt from usurious money, because usurious money is spent on charitable and good causes, and relieving the distress of the debtor by paying his debt is included therein.