Is it permissible to complete a contract for purchasing a tourist apartment that includes usurious terms or two sales in one, and how can one withdraw from this contract after signing it and paying part of the amount?

A Muslim must learn the rulings of his religion. The questioner erred by not being aware of the Sharia rulings concerning commercial contracts and by not paying attention to the conditions of the sale contract. Clauses and conditions that violate Sharia make the contract usurious (ribawi), and it is not permissible for a Muslim to enter into such a contract. If he can annul it, he must do so. Stipulating a penalty for late payment is forbidden usury (riba), as is agreeing on two different prices before concluding the contract. As for reducing a deferred debt for prompt payment (al-hatita min al-dayn al-mu'ajjal li-ajl ta'jeelih), it is permissible if it was not based on a prior agreement. The last two clauses in the contract, which are the seller's right to annul the sale if the buyer fails to pay the installments without excuse or notification, do not appear to violate Sharia. The first and second clauses alone are sufficient to render the contract forbidden. If it is possible to annul the contract without harm and forgo the amount paid, then annul it. Otherwise, pay the full amount to end the commitment, or continue paying the monthly installments while being careful not to be late.