Wa `alaykum as-Salamu wa rahmatullahi wa barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
As for your question, this is not your responsibility. So, you should make du`aa’ for your father imploring Allah Almighty to forgive him for that sin. You can also give a charity on his behalf as a means of expiation for what he has done.
Responding to your question, Dr. Jamal Badawi, professor at Saint Mary’s University in Halifax, Nova Scotia, Canada, and a cross-appointed faculty member in the Departments of Religious Studies and Management, stated:
Interest-based mortgage loans are haram; some scholars made an exception to the prohibition of these loans with a number of strict conditions such as the crucial need for a home to be the primary residential home, not intended for commercial purposes and only in the case of inaccessibility or the lack of alternative Islamically acceptable means of finance.
In your case, even if such a loan was not acceptable Islamically, it is not your responsibility. Also, keeping in mind that the land is legitimately owned by your mother; I can see no reason to consider it haram for you to own it or use it.
In his response to your question, Prof. Dr. Monzer Kahf, Professor of Islamic Finance and Economics at Qatar Faculty of Islamic Studies, states:
Your father bears its sin. If you still have any payment on it, try to pay it all off as soon as you can to avoid any further interest.
Allah Almighty knows best.
Editor’s note: This fatwa is from Ask the Scholar’s archive and was originally published at an earlier date.