1. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from Muhammad ibn ‘Isa ibn ‘Ubayd from Yasin who has said that narrated to him ‘ Abd al-Rahman ibn abu ‘ Abd Allah who has narrated the following: “I once said to the Shaykh (a.s.), to instruct me about the case of a man who claims against another for owing him a certain right but has no testimony to prove it. He (the Imam) said, ‘The defendant then must take an oath; and if he did so then he does not have any right, if he did not take an oath his right is established. If the defendant has died and testimony is established against him, then the plaintiff must take an oath by Allah, besides whom no one deserves to be worshipped, that so and so has died and that his right is on him. If he takes such an oath, otherwise, he has no right; we do not know, perhaps the deceased may have paid him in the presence of witnesses that we do not know their place or without testimony, before his death. For this reason oath is on the plaintiff with testimony, but if he claims without testimony he has no right because the defendant is not living; had he been living he had to take an oath or pay the right or turn the oath on the plaintiff in which case the right would not have been proved against him.”