Is it permissible for a judge to accept a lawsuit without supporting documents, and what is the evidence for that from the Qur’an and Sunnah?

If a case is brought before a judge, he must request evidence and proofs from the plaintiff, unless the defendant admits to the claim. If the defendant does not admit, and there is no evidence, then the oath is incumbent upon the defendant, based on the Prophet's (peace be upon him) saying: "Were people to be given according to their claims, some would claim the blood and wealth of men. But the oath is upon the defendant." And his saying: "The burden of proof is on the claimant, and the oath is on the defendant."