Jonah 3:9

Consider, if God had chosen to demolish everything [in a recent earthquake], what we would have suffered. I say this, so that the fear of these events may remain sharp in you and may keep everyone's resolution firm. He shook us, but he did not destroy us. If he had wished to destroy us, he would not have shaken us. But since he did not wish to destroy us, the earthquake came in advance like a herald, forewarning everyone of the anger of God, in order that we might be improved by fear and prevent the actual retribution.He has done this even for foreign nations. "Yet three days, and Nineveh shall be overthrown." Why do you not overcome the city? You threaten to destroy it. Why do you not destroy it? "Because I do not wish to destroy, for this very reason I threaten." So what is the Lord saying? "Lest I enact my impending judgment, let my word go in advance and prevent my acting." Yet three days, and Nineveh shall be overthrown. Then the prophet spoke. Today these walls speak. I say this, and I do not cease saying it, both to the poor and to the rich: consider how great is God's anger. Consider how simple his requirement: let us abstain from evil! In a brief moment of time he shattered the mind and resolution of each one of us. He shook the foundations of our hearts.

Look here then, say you: I discover a self-incriminating case in the matter of the Ninevites, when the book of Jonah declares, "And God repented of the evil that He had said that He would do unto them; and He did it not." In accordance with which Jonah himself says unto the Lord, "Therefore I fled before unto Tarshish; for I knew that Thou art a gracious God and merciful, slow to anger, and of great kindness, and repentest Thee of the evil." It is well, therefore, that he premised the attribute of the most good God as most patient over the wicked, and most abundant in mercy and kindness over such as acknowledged and bewailed their sins, as the Ninevites were then doing. ... Certainly not, my reply is; God will never repent of an act of justice. And it now remains that we should understand what God's repentance means. For although man repents most frequently on the recollection of a sin, and occasionally even from the unpleasantness of some good action, this is never the case with God. For, inasmuch as God neither commits sin nor condemns a good action, in so far is there no room in Him for repentance of either a good or an evil deed. ... According, therefore, to this definition, the divine repentance takes in all cases a different form from that of man, in that it is never regarded as the result of improvidence or of fickleness, or of any condemnation of a good or an evil work. What, then, will be the mode of God's repentance? It is already quite clear, if you avoid referring it to human conditions. For it will have no other meaning than a simple change of a prior purpose; and this is admissible without any blame even in a man, much more in God, whose every purpose is faultless. Now in Greek the word for repentance (METANOIA) is formed, not from the confession of a sin, but from a change of mind, which in God we have shown to be regulated by the occurrence of varying circumstances.