My father has been investing in the stock market for a few years now. Even though he only invests in companies with legitimate businesses Islamicly, recently he learned that investment in some companies that deal with Riba banks is not permitted. To purify his money, he decided to donate all the profit he made. The question is: can this money be donated to his son who is married and in need of money to buy a house?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

If the father cannot buy a house for his son from his lawful earnings, it becomes lawful for this father to give his son from the mentioned benefits from interests to buy a house or to spend such on his necessary needs.  This is so, because spending on the son is an obligation on the father provided this son is poor.

If the father is unable to spend on his son, this son becomes like any other person who deserves the mentioned money (interest).

Allah knows best.