من لا يحضره الفقيه, volume 3, page 63

Hadith.3343 - It is narrated from Yasin Al-Dareer, from Abdul Rahman ibn Abi Abdullah, who said: I asked the Sheikh, meaning Imam Musa ibn Jafar Al-Kadhim (as), "Inform me about a man who claims a right against another man but has no evidence to prove his claim." Imam (as) said: "The defendant must take an oath. If he swears, then the claimant has no right. However, if the defendant refers the oath back to the claimant and the claimant refuses to swear, then he has no right either. If the person against whom the claim is made has died and evidence is presented against him, the claimant must take an oath by Allah (swt), there is no God but He (swt), that the deceased owed him the claimed right. If he swears, the claim is valid; otherwise, he has no right. This is because we do not know-perhaps the deceased settled the debt through evidence unknown to us or without evidence before his death. Therefore, an oath along with the evidence is required. If the claimant makes a claim without evidence, he has no right because the defendant is not alive. Had the defendant been alive, he would have been required to either take an oath, acknowledge the claim, or refer the oath back. Hence, no right is established for the claimant." [chapter-CHAPTER 27 - CHAPTER ON THE JUDGMENT REGARDING TWO CLAIMANTS EACH PRESENTING EVIDENCE THAT THE RIGHT BELONGS TO THEM] بَابُ حُكْمِ الْمُدَّعِيَيْنِ فِي حَقٍّ يُقِيمُ كُلُّ وَاحِدٍ مِنْهُمَا الْبَيِّنَةَ عَلَى أَنَّهُ لَهُ‌

Translation: Bab Ul Qaim Publications — attributed by Thaqalayn·The Arabic above is the original.