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.