TIME IS THE ESSENCE

A clause used in a contract to expedite performance of the contract. For example:

Completion of this sale shall take place on (date), and in this respect time is of the essence of the contract.

This means that completion of the contract by the agreed upon date becomes a term of the contact. If the other party cannot complete the contract by that date then the innocent party can rescind the contract and claim damages, or seek an order for specific performance in equity.