Indian Contract Act, 1872
137. Creditor's forbearance to sue does not discharge surety
Mere forbearance on the part of the creditor to sue the principal debtor or to enforce any other remedy against him, does not, in the absence of any provision in the guarantee to the contrary, discharge the surety.
B owes to C a debt guaranteed by A. The debt becomes payable. C does not sue B for a year after the debt has become payable. A is not discharged from his suretyship.