Praise be to Allaah.
If the bank buys a car from you then sells it to the
customer, and it gives you 500 dollars in return for referring the customer
to the bank, there is nothing wrong with that. It comes under the heading of
combining the brokerage and sales contracts. It does not matter that the
bank is non-Islamic if it is going to buy a car from you and then sell it to
But if the role of the bank is to provide finance and pay on
behalf of the customer without buying a car from you, then this in fact is a
riba-based loan which is haraam: the bank lends the customer money so that
he will pay it back with something extra added. In that case it is not
permissible to refer the customer to the bank, and it is not permissible for
you to take anything from the bank, because guiding people to that which is
haraam is not permissible.
See the answer to questions no.
It is permissible to sell the car to the riba-based bank
which will sell it to the customer, because legitimate transactions with
those who deal in riba are permissible. Hence the Sahaabah (may Allah be
pleased with them) dealt with the Jews, buying and selling and the like,
even though the Jews engage in riba.
And Allah knows best.