The statement encapsulates a core principle of contract law: parties are bound to fulfill their promises. This duty of performance is primarily codified in Sections 37 to 39 of the Indian Contract Act, 1872.

Obligation to Perform (Section 37):
Parties must “perform, or offer to perform, their respective promises,” unless performance is dispensed with or excused under the Act or any law. Actual performance is emphasized. If a tendered performance is rejected without justification, the tendering party is discharged from further liability.

Offer of Performance (Tender) (Section 38):
A tender is a valid attempt to perform the promise. If the promisee refuses acceptance, the promisor is excused from further performance and may sue for non-acceptance. A tender must be unconditional, made at the proper time and place, allow inspection (in case of goods), and provide the promisee a reasonable opportunity to ascertain compliance.

Refusal to Perform (Section 39):
If a party wholly refuses or incapacitates themselves from performing, the promisee may terminate the contract unless they have acquiesced. This includes anticipatory breach or repudiation.

Circumstances Excusing Performance:

• Impossibility (Section 56): Performance becomes impossible or unlawful, invoking the doctrine of frustration (Satyabrata Ghose v. Mugneeram Bangur & Co., 1954).
• Agreement to Dispense or Waiver (Section 63): Promisee may waive performance, accept lesser performance, or extend time.
• Reciprocal Promises (Sections 51-54): Hindrance by one party may discharge the other.
• Alteration of Contract (Section 62) or Operation of Law: Novation, rescission, or insolvency may excuse performance.

Conclusion:
The Act provides a structured framework mandating performance while offering equitable exceptions. Tender of performance ensures willing parties are protected, and doctrines like frustration or waiver maintain fairness. This balance safeguards contractual sanctity while accommodating practical realities, ensuring contracts remain enforceable yet flexible in unforeseen circumstances.