39. When the holder of an accepted bill of exchange enters into any contract with the acceptor which, under section 134 or 135 of the Indian Contract Act, 1872 (9 of 1872), would discharge the other parties, the holder may expressly reserve his right to charge the other parties, and in such case they are not discharged.
Negotiable Instruments Act, 1881
Section 39: Suretyship
Chapter III — Parties to Notes, Bills and Cheques
Source: official text of the Negotiable Instruments Act, 1881.