law: Indian Contract Act, 1872 
  63. Promisee may dispense with or remit
  
  performance of promise
  Every promisee may dispense with or remit, wholly or in part,
  
  the Performance of the promise made to him, or may extend the time for such
  
  performance, for may accept instead of it any satisfaction which he thinks fit.
   Illustrations 
  (a) A promises to paint a picture for B. B afterwards forbids
  
  him to do so. A is no longer bound to perform the promise.
  (b) A owes B 5,000 rupees. A pays to B, and B accepts, in
  
  satisfaction of the whole debt, 2,000 rupees paid at the time and place at
  
  which the 5,000 rupees were payable. The whole debt is discharged.
  (c) A owes B 5,000 rupees, C pays to B 1,000 rupees, and B
  
  accepts them, in satisfaction of his claim on A. This payment is a discharge of
  
  the whole claim.
  (d) A owes B, under a contract, a sum of money, the amount of
  
  which has not been ascertained. A, without ascertaining the amount, gives to B,
  
  and B, in satisfaction thereof accepts, the sum of 2,000 rupees. This is a
  
  discharge of the whole debt, whatever may be its amount.
  (e) A owes B 2,000 rupees, and is also indebted to other
  
  creditors. A makes an arrangement with his creditors including B, to pay them a
  
  14[composition] of eight annas in the rupee upon their respective
  
  demands. Payment to B of 1,000 rupees is a discharge of B's demand.