In any action or motion, if good cause therefor be shown or appear, the court or judge in vacation may order the plaintiff to file a more particular statement, in his respect, of the nature of his claim, or the facts expected to be proved at the trial, and may stay the action until a reasonable time after such order is complied with; and such statement must be made under the oath of the plaintiff, or some other credible person, to the effect that the affiant believes the same will be supported by evidence at the trial. But no such order shall be made if it appear that there has been unreasonable delay on the part of the defendant in applying therefor.