How do we know that Jesus is the testator of the New Covenant?

The concept of a testator is vital in understanding the New Covenant. Hebrews 9:16 clarifies that where there is a testament, there must necessarily be the death of the testator. Jesus fulfilled this by willingly laying down His life, thus activating the New Covenant promises. His sacrifice is what allowed the inheritance promised to the elect to become effective. This shows the depth of God's plan, as the covenant was established from eternity and executed at the appointed time by Christ's death.