What he means is somewhat as follows. Pharaoh was a vessel of wrath, that is, a man who by his own hard-heartedness had kindled the wrath of God. For after enjoying much long-suffering, he became no better, but remained unimproved. Wherefore he calls him not only "a vessel of wrath," but also one "fitted for destruction." That is, fully fitted indeed, but by his own proper self. For neither had God left out anything of the things likely to recover him, nor did he leave out anything of those that would ruin him, and put him beyond any forgiveness. Yet still, though God knew this, "He endured him with much long-suffering," being willing to bring him to repentance. For had He not willed this, then He would not have been thus long-suffering. But as he would not use the long-suffering in order to repentance, but fully fitted himself for wrath, He used him for the correction of others, through the punishment inflicted upon him making them better, and in this way setting forth His power. For that it is not God's wish that His power be so made known, but in another way, by His benefits, namely, and kindnesses, he had shown above in all possible ways. For if Paul does not wish to appear powerful in this way ("not that we should appear approved," he says, "but that you should do that which is honest,") [2 Corinthians 13:7], much less does God. But after that he had shown long-suffering, that He might lead to repentance, but he did not repent, He suffered him a long time, that He might display at once His goodness and His power, even if that man were not minded to gain anything from this great long-suffering. As then by punishing this man, who continued incorrigible, He showed His power, so by having pitied those who had done many sins but repented, He manifested His love toward man. But it does not say, love towards man, but glory, to show that this is especially God's glory, and for this He was above all things earnest. But in saying, "which He had afore prepared unto glory," he does not mean that all is God's doing. Since if this were so, there were nothing to hinder all men from being saved. But he is setting forth again His foreknowledge, and doing away with the difference between the Jews and the Gentiles. And on this topic again he grounds a defense of his statement, which is no small one. For it was not in the case of the Jews only that some men perished, and some were saved, but with the Gentiles also this was the case. Wherefore he does not say, all the Gentiles, but, "of the Gentiles," nor, all the Jews, but, "of the Jews." As then Pharaoh became a vessel of wrath by his own lawlessness, so did these become vessels of mercy by their own readiness to obey. For though the more part is of God, still they also have contributed themselves some little. Whence he does not say either, vessels of well-doing, or vessels of boldness (παρρησίας), but "vessels of mercy," to show that the whole is of God. For the phrase, "it is not of him that wills, nor of him that runs," even if it comes in the course of the objection, still, were it said by Paul, would create no difficulty. Because when he says, "it is not of him that wills, nor of him that runs," he does not deprive us of free-will, but shows that all is not one's own, for that it requires grace from above. For it is binding on us to will, and also to run: but to confide not in our own labors, but in the love of God toward man. And this he has expressed elsewhere. "Yet not I, but the grace which was with me." [1 Corinthians 15:10] And he well says, "Which He had afore prepared unto glory." For since they reproached them with this, that they were saved by grace, and thought to make them ashamed, he far more than sets aside this insinuation. For if the thing brought glory even to God, much more to them through whom God was glorified. But observe his forbearance, and unspeakable wisdom. For when he had it in his power to adduce, as an instance of those punished, not Pharaoh, but such of the Jews as had sinned, and so make his discourse much clearer, and show that where there were the same fathers, and the same sins, some perished, and some had mercy shown them, and persuade them not to be doubtful-minded, even if some of the Gentiles were saved, while the Jews were perishing; that he might not make his discourse irksome, the showing forth of the punishment he draws from the foreigner, so that he may not be forced to call them "vessels of wrath." But those that obtained mercy he draws from the people of the Jews. And besides, he also has spoken in a sufficient way in God's behalf, because though He knew very well that the nation was fitting itself as a vessel of destruction, still He contributed all on His part, His patience, His long-suffering, and that not merely long-suffering, but "much long-suffering;" yet still he was not minded to state it barely against the Jews. Whence then are some vessels of wrath, and some of mercy? Of their own free choice. God, however, being very good, shows the same kindness to both. For it was not those in a state of salvation only to whom He showed mercy, but also Pharaoh, as far as His part went. For of the same long-suffering, both they and he had the advantage. And if he was not saved, it was quite owing to his own will: since, as for what concerns God, he had as much done for him as they who were saved. Having then given to the question that answer which was furnished by facts, in order to give his discourse the advantage of other testimony in its favor, he introduces the prophets also making the same declarations aforetime. For Hosea, he says, of old put this in writing, as follows:
However seriously the Jews may have sinned by rejecting the gift of God, and however worthy they may be of death, nevertheless, because they are the children of good people, whose privileges and many benefits from God they have received, they will be received with joy when they return to the faith, because God’s love for them is stirred up by the memory of their ancestors.
That the Gentile then might not be puffed up, and say, "I am standing, do not tell me of what would have been, but what has been," he uses this consideration to bring him down, and says, "As concerning the Gospel, they are enemies for your sakes." For when you were called they became more captious. Nevertheless God has not even now cut short the calling of you, but He waits for all the Gentiles that are to believe to come in, and then they also shall come. Then he does them another kind favor, by saying, "As touching election, they are beloved for the fathers sakes." And what is this? For wherein they are enemies, punishment is theirs: but wherein they are beloved, the virtue of their ancestors has no influence on them, if they do not believe. Nevertheless, as I said, he ceases not to solace them with words, that he may bring them over. Wherefore by way of fresh proof for his former assertion, he says,
When the Gentiles believed, the Jews became even more obnoxious. But even now God has not stopped calling the Gentiles. He is waiting for all of them who are to believe to come in, and then the rest of the Jews will come as well.
[AD 407] John Chrysostom on Romans 9:22-23:24