After silencing his critics with sound logic, Jesus now turns his attention to other critics in the same crowd who look to test Jesus by demanding a sign from Him. Jesus points to the Ninevite's response to Jonah and the Queen of Sheba's response to Solomon as faithful points of reference for His hearers. Yes, they repented as Jonah's preaching and Solomon's wisdom, but we have One who is greater now calling us to repentance. 

As the crowds increased, Jesus said, “This is a wicked generation. It asks for a sign, but none will be given it except the sign of Jonah. For as Jonah was a sign to the Ninevites, so also will the Son of Man be to this generation. The Queen of the South will rise at the judgment with the people of this generation and condemn them, for she came from the ends of the earth to listen to Solomon’s wisdom; and now something greater than Solomon is here. The men of Nineveh will stand up at the judgment with this generation and condemn it, for they repented at the preaching of Jonah; and now something greater than Jonah is here.” (Luke 11:29–32, NIV)