Should he go for an interest-based mortgage if that is cheaper than renting?

Transferring money from one currency to another

It is not permissible for the vendor to charge extra to the one who makes late payments

Is It Permissible to Take Riba-Based Loan for a Need?

This is the essence of ribaa

Ruling on buying a mosque with an interest-based loan

Lender referring a third party to debtor for extra money

He wants to bring in a person to take his place in a ribaa-based investment bank account to save himself

Is it permissible to deal with ribaa in a ribaa-based society?

Helping people to buy used cars with ribaa (interest)