Midrash for Sanhedrin 178:5

והא יונה דהדרי ביה ולא אודעוהו יונה מעיקרא נינוה נהפכת אמרי ליה איהו לא ידע אי לטובה אי לרעה

But perhaps they [sc. the Heavenly Court] repented thereof?<span class="x" onmousemove="('comment',' When a prophecy of doom was revealed to a prophet, as in the case of Jonah, it might subsequently have been withdrawn and therefore the prophecy was suppressed. How then can that prophet be flogged? ');">⁹</span> — Had they repented, all prophets would have been informed. But in the case of Jonah they did repent, yet Jonah himself was not informed! — Jonah was originally told that Nineveh would be turned, but did not know whether for good or for evil.<span class="x" onmousemove="('comment',' I.e., whether 'turned' meant 'overturned', or 'turned to repentance'. ');">¹⁰</span>

Sifrei Devarim