Augustine of Hippo : They do not understand, that not even the proudest of spirits themselves could rejoice in the honor of sacrifices, unless a true sacrifice was due to the one true God, in whose stead they desire to be worshipped: and that this cannot be rightly offered except by a holy and righteous priest; nor unless that which is offered be received from those for whom it is offered; and unless also it be without fault, so that it may be offered for cleansing the faulty. This at least all desire who wish sacrifice to be offered for themselves to God. Who then is so righteous and holy a priest as the only Son of God, who had no need to purge His own sins by sacrifice, neither original sins, nor those which are added by human life? And what could be so fitly chosen by men to be offered for them as human flesh? And what so fit for this immolation as mortal flesh? And what so clean for cleansing the faults of mortal men as the flesh born in and from the womb of a virgin, without any infection of carnal concupiscence? And what could be so acceptably offered and taken, as the flesh of our sacrifice, made the body of our priest? In such wise that, whereas four things are to be considered in every sacrifice,—to whom it is offered, by whom it is offered, what is offered, for whom it is offered,—the same One and true Mediator Himself, reconciling us to God by the sacrifice of peace, might remain one with Him to whom He offered, might make those one in Himself for whom He offered, Himself might be in one both the offerer and the offering. — ON THE TRINITY 4.14.19 Ephrem the Syrian : "It was fitting that we should have such a high priest, holy, blameless, unstained, separated from sinners … who had no need, like those high priests, to offer sacrifices first for his own sins and then for those of the people; he did this once for all when he offered up himself," not for him but for the sins of humankind. — COMMENTARY ON THE EPISTLE TO THE HEBREWS John Chrysostom : "For such an High Priest also became us, who is holy, harmless, undefiled, separate from the sinners." Thou seest that the whole is said with reference to the manhood. (But when I say "the manhood," I mean the manhood having Godhead; not dividing one from the other, but leaving you to suppose what is suitable.) Didst thou mark the difference of the High Priest? He has summed up what was said before, "in all points tempted like as we are yet without sin." "For" (he says) "such an High Priest also became us, who is holy, harmless." "Harmless": what is it? Without wickedness: that which another Prophet says: "guile was not found in His mouth," that is, He is not crafty. Could any one say this concerning God? And is one not ashamed to say that God is not crafty, nor deceitful? Concerning Him, however, in respect of the Flesh, it might be reasonable to say it. "Holy, undefiled." This too would any one say concerning God? For has He a nature capable of defilement? "Separate from sinners." — Homily on Hebrews 13 Oecumenius : It is obvious from these things that he is speaking about Christ according to the flesh in the preceding statements and these as well. For how could he say such things about divinity and not be ashamed, attributing these things to that incomprehensible nature? Therefore, he is holy, who neglects none of the things owed to him. He is innocent, blameless, and without deceit. "For no deceit," he says, "was found in His mouth." (Is. 53:9) "unstained."No one would call this a praise of God; for it is in his nature not to be defiled. But it is clear that this concerns the humanity of the one Christ. "separated from sinners." The chief priests among the Jews, he says, even if they were holy in other respects, as human beings they are still subject to evil and are not entirely separated from sinners; for how could they be, if they themselves are guilty of sins? "and exalted above the heavens." For He sat down on the throne of the Father. But does the term "exalted" not cry out that he speaks about His flesh? For the Word of God was always higher than the heavens. — The Pseudo-Oecumenian Catena on Hebrews Tertullian : For to this end had He come, that, being Himself pure from sin, and in all respects holy, He might undergo death on behalf of sinners. — On Modesty