Is it permissible for a person who stole money from his employer, and repented of his act, to deduct his overdue salaries and compensations from the stolen amount, and then secretly return the remainder? And is the employer guaranteed the money that was stolen from his office? And what is the ruling on money with which a car and a house were bought through usurious loans?

Your friend must hasten to absolve himself of the wrongs committed by returning the money he embezzled from his employer without informing him of the reason. As for the money stolen from his office and the salaries for the period of dismissal, the employer is not obliged to pay them unless he permitted him to continue working without termination, or if the contract was terminated without valid excuse. He is entitled to benefit from the house and car he purchased with an interest-based loan, because the prohibition of the loan pertains to his own liability, along with the obligation to repent from embezzlement and usurious transactions.