Article 1385-4 of the French Civil Code
The oath is evidence only in favour of or against the person who has referred it and his heirs and assigns. The oath referred by one of the joint and several creditors to the debtor discharges the debtor only in respect of that creditor’s share. The oath referred to the principal debtor also discharges the sureties. The oath referred to one of the joint and several debtors benefits the co-debtors….