From the route of Ibn ^Abbas, may Allah accept both of their deeds, who said that the Messenger of Allah, sallallahu ^alayhi wa sallam, said:
<<If people were to be given according to their claims then there would be men who would claim the money of others and that death penalty is due on them. However, the burden of proof is on the plaintiff and the oath is incumbent upon the defendant.>>
This Hadith is Hasan and is narrated in the same above stated terminology by al-Bayhaqiyy and others. Part of this terminology is narrated in the two Sahih books.