When God saw what they did, how they turned from their evil way, then God relented of the disaster that he said he would do to them, and he did not do it.
“and he did not do it.” Jonah’s prophecy was conditional, even though nothing in the text says it was. Most prophecies are conditional and can be altered by the behavior of the person or people receiving the prophecy (cp. Ezek. 33:11-20).