Matthew 12:40
For just like Jonah was in the stomach of the huge fish for three days and nights, so the Son of man will be in the heart of the earth [i.e., the cave-tomb] for three days and nights.
Matthew 16:4
"It is an evil and spiritually unfaithful generation of people [that keeps on] looking for a [supernatural] sign; but there will be no [such] sign given to it except the sign of Jonah [i.e., being in the huge fish for three days]." Then He left them and went away.
Luke 11:30
For just like Jonah became a sign to the people of Nineveh [Note: Nineveh was the capital of ancient Assyria], so the Son of man will also be [a sign] to this generation of people.