Is it permissible for a mother to buy gold earrings instead of her son, who is in straitened circumstances and to whom she lent gold earrings, and to make their price a debt upon him, given that this is before the price of gold increases?

The questioner wants to make the price of the earrings she will buy a debt owed by her son, instead of the earrings he previously borrowed from her. This is not permissible because it involves several prohibitions: settling an existing debt with a deferred payment, selling gold for money on credit, and selling debt for debt. Therefore, the son's liability remains only for the gold earrings he borrowed.