Is it permissible to conduct a transaction for purchasing a house through Murabaha with an Islamic bank, such that the bank buys the house for 100 dinars, and the buyer pays an additional 20 dinars to the seller via post-dated checks after the completion of the sale, knowing that the seller and the buyer will agree to show only 100 dinars to the bank?

The transaction mentioned is only valid if the questioner first purchases a common or specified share of the property from the seller, then the bank purchases the remaining part of the property, and after that, the questioner purchases this part from the bank.

However, paying a portion of the price to the seller while concealing it from the bank renders the transaction usurious (riba). In this case, the bank would have paid part of the price on behalf of the questioner and then recoups what it paid with an increase. This contradicts the Sharia (definition) standards which require the annulment of any prior contractual link between the client and the original seller to avoid the transaction transforming into a usurious loan.