Jonah 3:4

[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. […]

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.

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.

For He never makes a public display of our sins, except at any time He sees men insensible to them. For when He says "ye saw me hungry, and fed me not: and thirsty and gave me no drink," He speaks thus at the present time in order that we may not hear these words in time to come. He threatens, He exposes us in this world, that He may not have to expose us in the other: even as He threatened to overthrow the city of the Ninevites for the very reason that He might not overthrow it. For if He wished to publish our sins He would not announce beforehand that He would publish them: but as it is He does make this announcement in order that being sobered by the fear of exposure, if not also by the fear of punishment we may purge ourselves from them all.