"A surety has to pay what they owe, for whom he is engaged; to do, what is to be done by them, which they cannot perform. 'And if this be not the notion of a surety in this place, the apostle makes use of a word, nowhere else used in the whole scripture, to teach us what it doth never signify among people, which is improbable and absurd.' For the sole reason why he did make use of it was, that from the nature and notion of it among people, in other cases, we may understand the signification of it, and what, under that name, he ascribes unto the Lord Jesus" - Owen.
Having thus proved that εγγυος enguos is properly translated "surety," and that Christ is so styled, in a sense not widely different from what is usually attached to the word - let us next inquire, how Christ discharges this suretyship, or what he does in his capacity of surety? Is he surety to us for God? This last question, by orthodox writers, is for the most part, answered in the negative on the ground that there can be no need of security for God, his promise and his oath being sufficient guarantee that he will fulfil his engagement; on the ground also, that a surety must be some one greater than the party for whom he engages, which, in the case of God, renders the thing impossible, since there is none greater than Heb. Thus, Dr. Owen has argued at great length, and is followed by Guyse, Boston, and many others. Yet there are not wanting writers of great reputation for learning and orthodoxy, who scruple not to say that Christ is surety "for God;" (see Mr. Scott on this place).
He undertook, on the part of the Father. that all the promises should be made good to the seed. He acts in the behalf of God toward us, and assures us of the divine favor. "If it be asked, what need was there of a Mediator to assure us of the fulfillment of the promises made by the God of truth, who cannot lie or deceive us, I answer, the same objection might be made against God's adding his oath to his promise, whereby he intended to give us the greater security of accomplishment? - Pierce. The exclusion of this idea from the suretyship of Christ, on the part of so many divines, doubtless arose from the improper use made of it by Socinians, who unwilling to admit that Christ had become bound for our debt of suffering and obedience, and, in this sense, was surety "for us," resolved the suretyship into a mere engagement "in behalf of God." They could not allow more, without allowing the atonement.
While, however, we see no necessity for discarding this idea, because it has been used for bad purposes, we maintain, that this is neither all, nor even the principal part, of the suretyship of Christ. Revert to the original notion of a surety. He is one who engages, in behalf of another, to pay a debt or discharge a duty, which that other may fail to pay or discharge. Christ engaged to stand in that relation toward us, and therefore he is the "surety for us God," that our debt shall be discharged. God the Father, on his part, engages, that Christ shall see his seed, that they shall be saved; and the Son of God, on his part, becomes bound for the debt of penalty and obedience. This is the covenant of redemption, "the counsel of peace" between the Father and the Son, before all worlds; Zechariah 6:13; Isaiah 53:10, Isaiah 53:12. It is unnecessary further to observe, that Christ, in his capacity of surety, has nobly redeemed his pledge, endured the penalty, and honored the precept of the broken law, and thereby secured for his people the blessings of the covenant.
continued...
Gill's Exposition of the Entire Bible
By so much was Jesus made a surety of a better testament. Or "covenant", for the word signifies both; and what is intended may be called both a testament and a covenant; a testament, because it is founded in the good will and pleasure of God, and respects an inheritance bequeathed by God the Father to his children, which was confirmed and comes to them by the death of Christ the testator; and a covenant, it being a compact or agreement made by the Father with Christ, as the representative of all the elect; in which promises and blessings of all sorts are provided and secured for them in him; and is called in Scripture a covenant of life and peace, because these are things concerned in it; and is commonly by men called the covenant of grace, because it springs from the grace of God, the subject matter of it is grace, and the end of it is the glory of God's grace: now this is better than the covenant of works broken by man, and which exposes him to the curse and condemnation of the law; or than the covenant of the Levitical priesthood, by which was no perfection; and the form of administration of it under the Gospel dispensation is better than that under the law, for it is now revealed more clearly, and administered without types, shadows, and sacrifices; and the extent of its administration is larger, reaching to Gentiles as well as Jews; and besides, it is now actually ratified and confirmed by the blood of Christ, which is therefore called the blood of the everlasting covenant: and of this testament or covenant Christ is the "surety"; the word signifies one that draws nigh: Christ drew nigh to his Father in the council of peace, and undertook to be the Saviour and Redeemer of his people he substituted himself in their place and stead; he interposed between the creditor and the debtor, and became surety for the payment of the debts of the latter, and so stood engaged for them, and in their room: Christ is not the surety for the Father to his people, but for them to the Father; as to satisfy for their sins, to work out a righteousness for them, to preserve and keep them, and make them happy; which is an instance of matchless love.
Jamieson-Fausset-Brown Bible Commentary
22. surety-ensuring in His own person the certainty of the covenant to us. This He did by becoming responsible for our guilt, by sealing the covenant with His blood, and by being openly acknowledged as our triumphant Saviour by the Father, who raised Him from the dead. Thus He is at once God's surety for man, and man's surety for God, and so Mediator between God and man (Heb 8:
Matthew Henry's Concise Commentary
7:11-25 The priesthood and law by which perfection could not come, are done away; a Priest is risen, and a dispensation now set up, by which true believers may be made perfect. That there is such a change is plain. The law which made the Levitical priesthood, showed that the priests were frail, dying creatures, not able to save their own lives, much less could they save the souls of those who came to them. But the High Priest of our profession holds his office by the power of endless life in himself; not only to keep himself alive, but to give spiritual and eternal life to all who rely upon his sacrifice and intercession. The better covenant, of which Jesus was the Surety, is not here contrasted with the covenant of works, by which every transgressor is shut up under the curse. It is distinguished from the Sinai covenant with Israel, and the legal dispensation under which the church so long remained. The better covenant brought the church and every believer into clearer light, more perfect liberty, and more abundant privileges. In the order of Aaron there was a multitude of priests, of high priests one after another; but in the priesthood of Christ there is only one and the same. This is the believer's safety and happiness, that this everlasting High Priest is able to save to the uttermost, in all times, in all cases. Surely then it becomes us to desire a spirituality and holiness, as much beyond those of the Old Testament believers, as our advantages exceed theirs.