pactum de non petando

from Bouvier's Law Dictionary, Revised 6th Ed (1856)
PACTUM DE NON PETANDO, civil law. An agreement made, between a creditor and 
his debtor that the former will not demand, from the latter the debt due. By 
this agreement the debtor is freed from his obligation. This is not unlike 
the covenant not to sue, (q.v.) of the common law. Wolff, Dr. de la Nat. 
Sec. 755. 
    

[email protected]