Hebrews 9:15-17

For this reason He is the Mediator and Negotiator of a new covenant [that is, an entirely new agreement uniting God and man], so that those who have been called [by God] may receive [the fulfillment of] the promised eternal inheritance, since a death has taken place [as the payment] which redeems them from the sins committed under the obsolete first covenant. For where there is a will and testament involved, the death of the one who made it must be established, for a will and testament takes effect [only] at death, since it is never in force as long as the one who made it is alive.