There will be no sign except the sign of Jonah

Mt 12:38-40
Then some of the Pharisees and teachers of the law said to him, “Teacher, we want to see a sign from you.” He answered, “A wicked and adulterous generation asks for a sign! But none will be given it except the sign of the prophet Jonah. 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.”

As the prophet Jonah was in the belly of the fish three days and three nights, so Jesus was in the tomb three days and three nights. After that, he was resurrected, overcoming the power of death, so that we might have the hope of living eternally.
There is no greater miracle than raising the dead. Providing eternal life, not a limited life which perishes after some decades, is the greatest miracle. Jesus said that the only miracle He would give was the miracle of Jonahㅡthe miracle of destroying death and giving eternal life.

God can perform the miracle of dividing the sea simply by His word; He can move a huge mountain and make the heavens fall. However, if God works such miracles, what is that to us?
God, who loves our souls, has given eternal life to us dying because of sin that leads to death, through the words of the New Covenant. When we see this miracle of giving eternal life through the words, we can find our God.