Nonpayment of a note secured by mortgage,

"x x x.
For nonpayment of a note secured by mortgage, the creditor has a single cause of action against the debtor. This single cause of action consists in the recovery of the credit with execution of the security. In other words, the creditor in his action may make two demands, the payment of the debt and the foreclosure of his mortgage. But both demands arise from the same cause, the nonpayment of the debt, and, for that reason, they constitute a single cause of action. Though the debt and the mortgage constitute separate agreements, the latter is subsidiary to the former, and both refer to one and the same obligation. Consequently, there exists only one cause of action for a single breach of that obligation. [The creditor] then, by applying the rule above stated, cannot split up his single cause of action by filing a complaint for payment of the debt, and thereafter another complaint for foreclosure of the mortgage. If he does so, the filing of the first complaint will bar the subsequent complaint. By allowing the creditor to file two separate complaints simultaneously or successively, one to recover his credit and another to foreclose his mortgage, we will, in effect, be authorizing him plural redress for a single breach of contract at so much cost to the courts and with so much vexation and oppression to the debtor. (Bachrach Motor Co., Inc. v. Icarangal, 68 Phil. 287, 293-294 [1939]).
x x x."