Heb 13:8

“And if "today" means the whole present age, "yesterday" is probably the bygone age. This what I have understood to be the meaning in the psalm and in Paul's epistle to Hebrews. In the psalm it says: "A thousand years are in your eyes as a yesterday that has passed." Whatever the much talked of millennium means, it is likened to yesterday as opposed to today. And in the apostle writes, "Jesus Christ is the same yesterday and today and forever." No wonder that the whole of an age counts with God as the space of a single day with us, and I think even less.”

“How, also, can He be changeable and mutable, who says indeed by Himself: "I am in the Father, and the Father in Me," and, "I and My Father are one;" and by the prophet, "I am the Lord, I change not?" For even though one saying may refer to the Father Himself, yet it would now be more aptly spoken of the Word, because when He became man, He changed not; but, as says the apostle, "Jesus Christ, the same yesterday, today, and for ever."”

“These names—righteousness, sanctification, redemption, resurrection … are still common to the one who is above us and to the one who came for our sake. But others are peculiarly our own and belong to that nature which he assumed. So he is called man, not only that through his body he may be apprehended by embodied creatures, whereas otherwise this would be impossible because of his incomprehensible nature; but also that by himself he may sanctify humanity and be, as it were, a leaven to the whole lump. Then, by uniting to himself that which was condemned, he may release it from all condemnation, becoming for all people all things that we are, except sin—body, soul, mind, and all through which death reaches. Thus he became man, who is the combination of all these; God in visible form, because he retained that which is perceived by mind alone. He is son of man both on account of Adam and of the Virgin from whom he came, from the one as a forefather, from the other as his mother, both in accordance with the law of generation and apart from it. He is Christ because of his Godhead. For this is the anointing of his manhood and does not, as is the case with all other anointed ones, sanctify by its action but by the presence in his fullness of the anointing one; the effect of which is that that which anoints is called human and makes that which is anointed God. He is the way, because he leads us through himself; the door as letting us in; the shepherd, as making us dwell in a place of green pastures and bringing us up by waters of rest, and leading us there and protecting us from wild beasts, converting the erring, bringing back that which was lost, binding up that which was broken, guarding the strong, and bringing them together in the fold beyond, with words of pastoral knowledge. The sheep, as the victim; the lamb, as being perfect; the high priest as the offerer; Melchizedek, as without mother in that nature which is above us and without father in ours; and without genealogy above for who, it says, shall declare his generation? and, moreover, as king of Salem, which means peace, and king of righteousness, and as receiving tithes from patriarchs, when they prevail over powers of evil. They are the titles of the Son. Walk through them, those that are lofty in a godlike manner; those that belong to the body in a manner suitable to them; or rather, altogether in a godlike manner, that you may become a god, ascending from below, for his sake who came down from on high for ours. In all and above all keep to this, and you shall never err, either in the loftier or the lowlier names. Jesus Christ is the same yesterday and today in the incarnation, and in the Spirit forever and ever. Amen.”

“In these words, "Jesus Christ the same yesterday and to-day and for ever," "yesterday" means all the time that is past: "to-day," the present: "for ever," the endless which is to come. That is to say: Ye have heard of an High Priest, but not an High Priest who fails. He is always the same. As though there were some who said, "He is not, another will come," he says this, that He who was "yesterday and to-day," is "the same also for ever." For even now the Jews say, that another will come; and having deprived themselves of Him that is will fall into the hands of Antichrist.”

“The natural properties of the Word who came forth from the Father were maintained even when he became flesh. It is foolish therefore to dare to introduce a breach. For the Lord Jesus Christ is one and through him the Father created all things. He is composed of human properties and of others that are above the human, yielding a kind of middle term. He is, in fact, a mediator between God and humankind, according to the Scriptures, God by nature even when incarnate, truly, not purely man like us, remaining what he was even when he had become flesh. For it is written, "Jesus Christ is the same yesterday and today and forever."”

“How then could he be the same in the past when he had not yet assumed generation according to the flesh?… It is of Jesus Christ and not just of the Word that the text affirms that he is the same today, yesterday and forever, but how could the human nature possess immutability and unaltered identity when it is subject to movement and, above all, to that movement that made it pass from nothingness to being and to life?… In virtue of the union with flesh that is proper to him, it is still he himself who is described as existing yesterday and as preexistent.”

“The Son of God, assuming our likeness and becoming human, not taking up what he was but taking on what he was [i.e., the divine condition] effects our salvation. For he remains, as Paul put it, the same yesterday and today and forever, without undergoing any change in his divinity by reason of his incarnation, but remaining what he was and will always be.”

“This, too, he does not simply put down, but he fits it to the argument that has been interrupted, teaching that he was crucified by the Jews. And he also demonstrates his eternal existence, for he calls the human nature "yesterday and today" and names the divinity "forever." And he says that the two are the same, since the only begotten and the firstborn are one and the same Son.”

“For, it seemed, some were distorting the faith and saying that another would come, whom the Jews even now await. So he says that Christ is the same "yesterday," that is, in all past time, "and today," that is, in the present, and "forever," that is, in future and endless times, and another will not come. So do not be led astray. Or: just as He did not abandon your teachers, but helped them in everything, so also will He render help to you. For He is one and the same.”

“He continues: Jesus Christ, yesterday, and today: and the same forever. According to a Gloss this is the way this section is introduced. For he had said before, I will not leave you or forsake you. But they could say: The one to whom this was said can well trust in God's help, but not we to whom it was not spoken. But the Apostle rejects this, saying that Christ remains forever; hence, he says, Jesus Christ, yesterday, and today: and the same forever. Or it can be referred to what he had just said, namely, that they should imitate the apostles. They could say that the case is not the same, because they were instructed by Christ and served Him, but we not so. Therefore, the Apostle says that Christ remains; hence, he says that we should serve Him. And so he says, Jesus Christ, yesterday, namely, in the time of the first apostles, and today, namely, in their time, and the same forever: 'I am with you all days even to the consummation of the world' (Mt. 28:20); 'Says the Lord, who is, and who was, and who is to come, the Almighty' (Rev. 1:8); 'But you are always the selfsame, and your years shall not fail' (Ps. 101:28). In these words he shows the eternity of Christ.”