Matthew Poole and continuators on Hebrews 9:16

16 For where a testament is, there must also of necessity be the death of the testator ,

For, gives the reason of the Mediator's Death, even the putting the Called into the possession of the bequeathed Inheritance, demonstrated by a common, natural Law in all Nations of the Testament effect on the Testators Death: A Testament being a disposition by Will nuncupative, or written, of either Goods or Lands, which are the persons own, to be the Right and Possession of others after his Death, whom he nominateth in it: such in proportion is the New Covenant, where God gives freely all spiritual good things with an Heavenly Inheritance, as Legacies to all his Called Ones in Christ, by this last and best Will and Testament of his, written in his Scripture-Instrument, witnessed by the Prophets and Apostles, sealed by the two Sacraments, especially the Lord's Supper, Luke 22.20.

He who maketh a Testament by the Law of Nature as of Nations, must die before the Legatees have any profit by the Will, the Son and Heir inherits not but on the Father's Death; then is the Testament firm and valid, the time being come for the Heirs inheriting, and for the Wills execution, it being now unalterable; the necessity of which is cleared v. 17.

Marginal references: Or, brought it.