No sheriff or deputy sheriff shall be required to advertise the property of any defendant in execution for sale until the cost of the advertisement shall have been first paid by the plaintiff in execution, his agent, or his attorney, provided that when any such party plaintiff, or his agent or attorney for him, shall make and file an affidavit in writing that because of his indigence he is unable to pay such cost, it shall be the duty of the sheriff or his deputy to proceed as required by law.