Matthew Poole and continuators on Hebrews 7:22

22 By so much was Jesus made a surety of a better testament .

This brings in the Consequent on v. 20. As much Excellency as was in God's Oath constituting, so much there must be in the Office constituted. The Aaronical Priesthood by God's Constitution, was excellent; but Christ's is much more so, being by God's Oath made personal and everlasting, relating to the best Covenant; so as the Hebrews had the greatest reason to renounce Aaron's, and to cleave to Christs for Salvation. He being God-Man, is a Surety, one that bindeth himself for another, to see something paid or performed, to give security for another; and is proper to him as a Priest, Iob 17.3. Psal. 119.122▪ Prov. 6.1. In the Mosaical Oeconomy the Priests were typical Sureties, or Undertakers for the People; so Aaron, as a Surety, was sent by Moses to stand between the Living and the Dead, when God was cutting off those Sinners, Numb. 16.46, 48. The Spirit interprets this Surety, to be a Mediator, ch. 8.6. which is the general comprehensive Name of all his Offices; as he gives all from God to us in and by his Promises, he is Testator fulfilling them, ch. 9.15, 16. As he gives satisfaction to God for us, and returns our Duty performed with the Incense of his Merits. He is our Surety; which merit of his resulted from his perfect Obedience to the whole Law and Will of God, and from the full Satisfaction he made to God by his Death for our Sins. Rom. 5.19. 2 Cor. 5.21. Gal. 3.13.

The Gospel-Covenant described, ch. 8.10, 11, 12. and referreth to what the Lord foretold of it, Ier. 31.33, 34. which is better than the Mosaical for Perspicuity, Freeness, Fulness, Spirituality, and the Spirit promised in it for its Ratification by the Death of Christ and its Perpetuity; See ch. 8.8, 9, 11.