What is the ruling on working in a furniture store where the employer demands lying to customers about the origin of the goods (China instead of Spain)? What is the ruling on an employee increasing the set price and taking the excess for himself? Is the money earned from this considered unlawful? And what should one do if they are unable to return the funds?

Lying and cheating in sales are major forbidden acts and erase blessings. The cheater must repent to Allah and inform his partner of his mistake. The ill-gotten money taken due to cheating must be identified and returned to its rightful owners, or their heirs, or spent on Muslim welfare if they cannot be identified. If the partner refuses to return the right, then the person who directly engaged in cheating must return it. As for the money you received as wages for your work, it is lawful. Any excess beyond the shop's set price must be returned to the shop owner. The promised increase every three months, if stipulated in a contract, you are entitled to it; but if it was merely a promise, you are not entitled to it.