John Trapp on Jonah 3:9

Verſe 9. Who can tell if God will turn and repent] This is the ſpeech of one that doubteth, and yet deſpaireth not: like that of David praying for his ſick child, Who can tell whether God will be gratious to me that the child may live 2 Sam. 12.22. We are ſtaggering, ſaith Saint Paul, but not wholy ſticking 2 Cor. 4.8. They that go down to the pit (of deſpaire, as well as of the grave Eſ. 38.18.) cannot hope for thy truth: but are hurried headlong into hell, as the Gergeſites ſwine were into the ſea. The Prophet Jonah was peremptory, that by ſuch a day Niniveh ſhould be deſtroyed: Theſe men therefore had good reaſon to doubt, if not of the pardon of their ſins, yet of the ſaving of their city. All their hope is, that this that Jonah denounced was not Gods abſolute decree, but onely his threatening, and that conditionall too; viz. except they repented. This if they could do, and heartily, they knew not but that mercy might be yet had. Keep hope in heart, or the work will go on heavily Pſal. 43. ult. Hope is the daughter of Faith: but ſuch as is a ſtaff to her aged mother. See the Note on Ioel. 2.14. Of God repenting I have ſpoken elſewhere.