Luke 11:29 KJV
And when the people were gathered thick together, he began to say, This is an evil generation: they seek a sign; and there shall no sign be given it, but the sign of Jonas the prophet.
Luke 11:29, King James Version
In context
28 But he said, Yea rather, blessed are they that hear the word of God, and keep it.
29 And when the people were gathered thick together, he began to say, This is an evil generation: they seek a sign; and there shall no sign be given it, but the sign of Jonas the prophet.
30 For as Jonas was a sign unto the Ninevites, so shall also the Son of man be to this generation.