Is it permissible to participate in a government project for purchasing a house in installments, which involves the state paying part of the installment with 2% interest, knowing that withdrawing from the project leads to the loss of a $10,0 down payment, and is there a way to purify the money and the house if one participates?

The state pays part of the house's price to the company, and the subscriber repays the money with an increase; this is an interest-based loan (riba).

If the enquirer has already subscribed, he is not obligated to withdraw, but he must repent, and the house is not unlawful. However, if he has not yet subscribed, then it is not permissible for him to enter into it except out of necessity or a need that is ordinarily difficult to bear.