In Matthew 12:38-42, Jesus said the only sign given to this unbelieving generation about Himself, will be the sign of Jonah. For just as Jonah was in the belly of a whale for three days and nights, so shall the Son of Man be in the Earth for a like period of time.

And just as Jonah was spit out of the whale’s mouth in order to preach to the people of Nineveh, so did Jesus resurrect from the tomb, and 40 days later, ascend back to the Father, where He again received the full thrust of heavenly glory He once had before emptying Himself to become a human.

Of course, Jesus’ resurrection and ascension is exponentially more important to everybody’s salvation than Jonah’s was to just the Ninevites.