And God saw their works, that they turned from their evil way; and God repented of the evil, that he had said that he would do unto them; and he did it not. (Jonah 3:10)
Commenting on the book of Jonah and the contingent nature of prophecy therein, Thomas Bolin noted the following:
Jonah and prophecy. Taking as a cue Jonah’s inclusion in the Book of the Twelve, some exegetes hold that the book is a commentary on Israelite prophecy. Beyond this point scholars part company. Among the views held are the following: a prophet cannot escape divinely ordered duty; the honor and validity of a prophet whose message has not come to pass does not matter in light of the divine sovereignty; the book is an explanation of the non-fulfillment of other prophetic oracles (specifically those of an apocalyptic nature);it is a critique of prophets of woe and those for whom the prophetic word is unconditional; it is a critique of prophecy in general as a decrepit institution of petty practitioners; it is a lesson to its readers of how a city or people ought to respond . . . The notice that God repented of the pronounced doom upon seeing the repentance of the Ninevites has caused consternation among those who hold that no causality exists between human action and divine response. However, 3.10 is clear that Yahweh changes his mind only after seeing how the Ninevites change their ways. The same term (שׁוב) is used to speak of both Yahweh’s and the other Ninevites’ change. (Thomas M. Bolin, Freedom Beyond Forgiveness: The Book of Jonah Re-Examined [JSOT 236; Copenhagen International Seminar 3; Sheffield: Sheffield Academic Press, 1997], 60-61, 128-29)
For more on the book of Jonah and the contingent nature of prophecy, see: