When summons of garnishment shall issue before judgment against the defendant, the defendant may at any time traverse the plaintiff's affidavit upon which the garnishment was obtained, stating that the affidavit is untrue or legally insufficient. Upon filing of the traverse, the court from which the garnishment issued shall issue a show cause order to the plaintiff requiring him to appear at a specified time, which shall not be more than ten days from the filing of the traverse, to prove the grounds for the issuance of the garnishment. If the plaintiff shall fail to carry the burden of proof, the order authorizing the garnishment prior to judgment shall be revoked.