Hebrews 13:20

"The blood of the eternal covenant," not through that which passes away but through the one which remains forever, that is, Jesus Christ our Lord.

"the God of peace." First, asking for their prayers and honoring them even in this way, Paul himself also prays for them. Since, he says, God is peace, you ought not to be stirred up against me from mere gossip and to have hostility. "who brought up from the dead the great Shepherd of the sheep." Which one? Our Lord, he says, Jesus. He affirms to them a certain word about the resurrection, taking the use from the prophecy of Isaiah (Isa. 40:11). And while there were also other shepherds, minor ones, he said the great one. For many are the prophets and teachers, but one is the instructor, Christ. "by the blood of the eternal covenant." That is to say, He raised him from the dead who had died, and having poured out his blood, that this might be for us an eternal covenant, that is, not to be cancelled, as the legal one, but everlasting. Thus: He raised him from the dead by the blood of an eternal covenant. For when he was raised, his blood was granted to us for an eternal covenant. For if he had not been raised, his blood would not have been for us a covenant.

Therefore having first asked their prayers, he then himself also prays for all good things on them. "Now the God of peace," he says (be ye not therefore at variance one with another), "that brought again from the earth the Shepherd of the sheep" (this is said concerning the resurrection) "the Great Shepherd" (another addition: here again he confirms to them even to the end, his discourse concerning the Resurrection) "through the blood of the everlasting covenant, our Lord Jesus Christ," "make you perfect in every good work, to do His will, working in you that which is well-pleasing in His sight." Again he bears high testimony to them. For that is made "perfect" which having a beginning is afterwards completed. And he prays for them which is the act of one who yearns for them. And while in the other Epistles, he prays in the prefaces, here he does it at the end. "Working in you," he says, "that which is well-pleasing in His sight through Jesus Christ, to whom be glory for ever and ever. Amen." Seest thou how he shows that virtue is born neither wholly from God, nor yet from ourselves alone? First by saying, "make you perfect in every good work"; Ye have virtue indeed, he means, but need to be made complete. What is "good work and word"? So as to have both life and doctrines right. "According to His will, working in you that which is well-pleasing in His sight." "In His sight," he says. For this is the highest virtue, to do that which is well-pleasing in the sight of God, as the Prophet also says, "And according to the cleanness of my hands in His eye-sight." (Ps. xviii. 24.)