The Indian Contract Act, 1872
136. Surety not discharged when agreement made with third person to give time to principal debtor
Where a contract to give time to the principal debtor is made by the creditor with a third person, and not with the principal debtor, the surety is not discharged.
C, the holder of an overdue bill of exchange drawn by A as surety for B, and accepted by B, contracts with M to give to B. A is not discharged.