Is it permissible for a mother to give the profits from an investment certificate to her son to help him with marriage expenses, such as furnishing an apartment?

Investment certificates issued by usurious banks are a prohibited transaction, and their profits are usurious interest that must be disposed of by spending it on charitable causes and for the benefit of Muslims. It is permissible to give it to a poor, needy son, but it is not permissible to give it to a rich one.