Expositor's Bible Commentary Commentary Luke 11:30

"For even as Jonah became a sign unto the Ninevites, so shall also the Son of man be to this generation." — Luke 11:30 (ASV)

The “sign” Jesus provided to those who wanted one (cf. v.16) is the sign of Jonah himself, whose presence and brief message (cf. v.32), though more minimal compared with the preaching of Jesus, triggered immediate and widespread repentance. The preaching of Jesus carried its own authority, especially when affirmed by the power of God in miracles (e.g., 4:32, 36).