What is the legal basis for ruling in favor of the plaintiff when the defendant abstains from taking the decisive oath, despite it being requested and notified to him?

The court relies on the principle: 'The burden of proof is on the claimant, and the oath is on the one who denies.' If the plaintiff requests the defendant's oath, and the defendant is notified of the decisive oath but abstains from it by not attending or refusing, the court may rule against him based on his abstention from the oath, in accordance with Article 2, Paragraph (1), Article 96, Paragraph (1), and Article 98 of the Law of Evidence.