Albert Barnes Commentary Hebrews 9:20

"saying, This is the blood of the covenant which God commanded to you-ward." — Hebrews 9:20 (ASV)

Saying, This is the blood of the testament. Of the covenant. (See Barnes on Hebrews 9:16-17).

That is, this is the blood by which the covenant is ratified. It was the means used to confirm it; the sacred and solemn form by which it was made sure. When this was done, the covenant between God and the people was confirmed—as a covenant between man and man is when it is sealed.

Which God hath enjoined unto you. In Exodus 24:8, which God hath made with you. The language used by Paul, which God hath enjoined — eneteilato — commanded — shows that he did not regard this as strictly of the nature of a covenant, or compact. When a compact is made between parties, one does not enjoin or command the other, but it is a mutual agreement.

In the transactions between God and people, though called Berith — or diayhkh — diatheke — the idea of a covenant or compact is so far excluded that God never loses his right to command or enjoin. It is not a transaction between equals or an agreement; it is a solemn arrangement on the part of God which he proposes to people, and which he enjoins them to embrace; which they are not indeed at liberty to disregard, but which, when embraced, is appropriately ratified by some solemn act on their part. (Compare Barnes on Hebrews 8:6).