Matthew 12:38-41New International Version - UK (NIVUK)
The sign of Jonah
38 Then some of the Pharisees and teachers of the law said to him, ‘Teacher, we want to see a sign from you.’
39 He answered, ‘A wicked and adulterous generation asks for a sign! But none will be given it except the sign of the prophet Jonah. 40 For as Jonah was three days and three nights in the belly of a huge fish, so the Son of Man will be three days and three nights in the heart of the earth. 41 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.
Matthew 16:1-4New International Version - UK (NIVUK)
The demand for a sign
16 The Pharisees and Sadducees came to Jesus and tested him by asking him to show them a sign from heaven.
2 He replied, ‘When evening comes, you say, “It will be fair weather, for the sky is red,” 3 and in the morning, “Today it will be stormy, for the sky is red and overcast.” You know how to interpret the appearance of the sky, but you cannot interpret the signs of the times.[a] 4 A wicked and adulterous generation looks for a sign, but none will be given it except the sign of Jonah.’ Jesus then left them and went away.