What portion of a debt is established if one of two heirs swears an oath alongside a witness?

Primary text

If one of two sons swears an oath in support of a witness regarding a debt, only the portion corresponding to his share is established. Similarly, if heirs claim a bequest (wasiyya) or a debt owed to their father and present one witness, the entire claim is not established unless all heirs swear. If only some of them swear, the debt or bequest is established only to the extent of their shares, and the remaining heirs do not share in what is established by the oath of others. This is because the right does not become established for the remaining heirs without their own oaths, nor is it permissible for them to benefit from the oath of another.