The dominant metaphor in this section [Hebrews 9:15-28] is the picture of an inheritance that is delivered by the owner of an estate to his legal heirs. Since Jesus is a High Priest, the inheritance that he bequeaths is not a piece of land but his priestly office and its resources (9:15), for like the priests of the OT who inherited their status and livelihood from God (Num 18:20; Deut 14:27, 29), the inheritance of God’s people comes from their place in his house. It involves their access to his heavenly sanctuary and its resources. Their inheritance is in heaven with God (9:23-27).
As with any human inheritance, three conditions apply to their reception of their inheritance from him. First, there must be a valid will, a publicly attested testament made by the owner of an estate in which he names those whom he has chosen as his heirs (9:15). Second, the owner of the estate must have died before his heirs can receive their share of his estate (9:16-17). Third, the heirs have to be free citizens. Since Christ’s heirs were enslaved to death and the devil (2:14-15) and in debt to God for their sins against him (9:15), Christ ransomed and released them by his blood (9:15, 22, 26, 28).
John W. Kleing Concordia Commentary: Hebrews 452-453