The duty of honest contractual performance, as established in the Bhasin case, requires the parties to be forthright, candid, and not misleading in their dealings with each other. This duty applies to the performance of all contracts, and its purpose is to enhance the fairness, efficiency, and predictability of contractual dealings.

In the scenario you provided, if it can be established that XYZ Ltd rejected potential subtenants solely to harm the business of ABC Ltd, it could be considered a violation of the duty of honest contractual performance. This duty obliges the parties to act honestly in their contractual dealings and not to intentionally undermine the other party's interests. By intentionally keeping the space vacant to make ABC Ltd's mall less attractive and busy, XYZ Ltd may be in breach of the duty of honest contractual performance.