Cancellation of a contract

It is an annulment as far as the contracting parties are concerned, and a new contract as far as a third person who may be involved.   [An example of this would be in the following where a person who had a right to purchase property (probably by being a neighbour) and he waives his right to someone else. This person buys the property and thereafter the sale is cancelled. Now the first person can reclaim his right to purchase, as it will be a new contract between him and the owner] (Kitaabul Buyoo).