Jonah used this rhetorical question to show God how angry he was. Also, what Jonah said when he was back in his own country can be stated explicitly. Alternate translation: "When I was still in my own country I knew that if I warned the people of Nineveh, they would repent, and you would not destroy them" (See: [[rc://en/ta/man/translate/figs-rquestion]] and [[rc://en/ta/man/translate/figs-explicit]])
# because I knew that you are a gracious God... and you hold back from sending disaster
This was Jonah's reason for going to Tarshish instead of to Nineveh. He did not want to go to Nineveh and preach to the people there, because he did not want them to turn from their sins, and he he did not want God to be kind to them.
This means "you say that you will send disaster on sinners, but then you decide not to." Alternate translation: "you decide not to punish people who sin"