We are working on public holidays, but we do not get paid for overtime. Should the employer give us the overtime payment? What is the rule in Islam?
This depends on your contract between you and your employer. If it was agreed beforehand for overtime payments for public holidays, the employer must pay. If it was not mentioned during the agreement, then the general practice in your profession should be considered. If the general practice is (either legally or de facto) upon paying the overtimes for public holidays, the employee has the right to ask for overtime payment.