Matthew 16:4

16:4 A wicked and adulterous generation asks for a sign, but no sign will be given to it except the sign of Jonah.” Then he left them and went away.

Luke 11:29-30

The Sign of Jonah

11:29 As the crowds were increasing, Jesus began to say, “This generation is a wicked generation; it looks for a sign, but no sign will be given to it except the sign of Jonah. 11:30 For just as Jonah became a sign to the people of Nineveh, so the Son of Man will be a sign to this generation.