Let us turn to every age that has passed, and learn that, from generation to generation, the Lord has granted a place of repentance to all such as would be converted unto Him... Jonah proclaimed destruction to the Ninevites; but they, repenting of their sins, propitiated God by prayer, and obtained salvation, although they were aliens [to the covenant] of God.
Does God for our salvation deceive and say certain things so that the sinner ceases doing what he might do if he had not heard certain of these words? Was the one who says, “Yet three days and Nineveh shall be destroyed,” speaking as one who speaks truly or not? Or as one who deceives by a deceit that converts? If that kind of conversion did not happen, was what was said no longer a deceit but already truth. There would have been a destruction that followed for Nineveh. It was up to those who hear.
God threatens to destroy the city of Nineveh for the very reason that He might not destroy it. When God makes a threat concerning our sins, He makes the threat beforehand so that we may be sobered by fear, so that our repentance will bring about God’s mercy so He will not have to follow through with the threat. (Hom. On Paralytic 3)
If you want, let us also hear this story: “Now the word of the Lord,” it says, “came to Jonah, saying, ‘Rise and go to Nineveh, the great city.’ ” He wanted to put Jonah to shame by sending him to the great city of Nineveh, because he foresaw the prophet’s escape. However, let us also listen to the preaching: “Yet three days, and Nineveh shall be overthrown.” Why do you, God, foretell the sufferings that you will inflict upon Nineveh? “So that I will not do what I announced.” This is why God threatened with hell—so he would not lead anyone away to hell. He says, “Fear that which is spoken to you, and do not be saddened about what has been done.” Why does he establish the appointed time to be only a period of three days? So that you may learn even the virtue of the barbarians—I call the Ninevites barbarians, who were able to annul in three days such anger caused by sin. I want you to marvel at the philanthropy of God, who was satisfied with three days of repentance for so many transgressions. I do not want you to sink into despair, even though you have innumerable sins.
"[And Jonah began to enter into the city a day's journey], and he cried, and said, Yet forty days, and Nineveh shall be overthrown." LXX: 'he proclaimed and said, another three days and Nineveh will be destroyed". The umber three written in the Septuagint does not agree with the penitence, and I am quite astonished at this translation, for in Hebrew neither the letters or syllables or accents or the word show any common element. For three is said, salos and forty arbaim. Moreover the prophet who was sent from Judea to the Assyrians was to claim after such a journey penitence worthy of his prediction to cure with a long-present dressing his old and putrid wounds. Moreover the number forty is appropriate to sinners, to hunger, to prayer, to sackcloth, to tears and to perseverance in prayer. In this way Moses fasted for forty days on mount Sinai [Ex. 34:28; Deut. 9:18] and Elijah fleeing Jezebel [3 Kings. 19:8] is presented to us as having fasted for forty days after having told Israel about the famine [3 Kings. 17:1], when the anger of God was upon them. And the Lord Himself, the true Jonah who is sent to preach to the world fasts for forty days [Mt. 4:2]. And he leaves us as hereditary fasting to prepare our spirits, by this number of forty, as the food of his body. "he cried out": the Gospel shows this expression more fully: "standing, he cried out in the temple: if anyone is thirsty, let him come to me and he shall drink" [John 7:37], for all speech of the Saviour is called a cry because he speaks about weighty subjects.
[Daniel 4:27] "'Wherefore, O king, let my counsel meet with thy favor, and make up for thy sins by deeds of charity, and thine iniquities by showing mercy to the poor. Perhaps God will forgive thy transgressions.'" Since he had previously pronounced the sentence of God, which of course cannot be altered, how could he exhort the king to deeds of charity and acts of mercy towards the poor? This difficulty is easily solved by reference to the example of King Hezekiah, who Isaiah had said was going to die (Isaiah 38:1); and again, to the example of the Ninevites, to whom it was said: "Yet forty days, and Nineveh shall be destroyed" (Jonah 3:4). And yet the sentence of God was changed in response to the prayers of Hezekiah and the city of Nineveh, not by any means because of the ineffectualness of the judgment itself but because of the conversion of those who merited pardon. Morever in Jeremiah God states that He threatens evil for the nation (Jeremiah 18:7-8), but if it does that which is good, He will alter His threats to bestow mercy. Again, He affirms that He directs His promises to the man who does good; and if the same man thereafter works evil, He says that He changes His decision, not with regard to the men themselves, but with regard to their works which have thus changed in character. For after all, God is not angered at men but at their sins; and when no sins inhere in a man, God by no means inflicts a punishment which has been commuted. In other words, let us say that Nebuchadnezzar performed deeds of mercy toward the poor in accordance with Daniel's advice, and for that reason the sentence against him was delayed of execution for twelve months. But because he afterwards while walking about in his palace at Babylon said boastingly: "Is this not the great Babylon which I myself have built up as a home for the king by the might of my power and the glory of my name?" therefore he lost the virtue of his charitableness by reason of the wickedness of his pride.
"It may be that God will forgive thy sins." In view of the fact that the blessed Daniel, foreknowing the future as he did, had doubts concerning God's decision, it is very rash on the part of those who boldly promise pardon to sinners. And yet it should be recognized that indulgence was promised to Nebuchadnezzar in return, as long as he wrought good works. Much more, then, is it promised to other men who have committed less grievous sins than he. We read in Jeremiah also of God's direction to the people of the Jews, that they should pray for the Babylonians, inasmuch as the peace of the captives was bound up with the peace of the captors themselves (Jeremiah 29:7).
We should not despair of those who are still unwilling to correct their vices and do not even blush to defend them. In a similar way hope was not abandoned for that city of which it is written, “Three days more, and Nineveh shall be destroyed”; yet in those three days it was able to be converted, pray, bewail and merit mercy from the threatened punishment. Therefore let all who are such listen to God while it is possible to hear him in his silence; that is, not punishing at present. For he will come and will not be silent, and he will then reprove when there is no chance of amendment.
[AD 99] Clement of Rome on Jonah 3:4-5