Jesus uses the story of Jonah as a parallel to his own mission. In the Gospel of Luke, this means that Jesus, like Jonah, has come from a long distance (from heaven!) and is preaching the need for repentance.
However, unlike the Ninevites, many Israelites resist Jesus' message and ask him to perform some sensational sign. Jesus tells them that, just as the power of Jonah's message was sign enough for the people of Nineveh, so the power of his message should be sign enough for all generations.
You can learn a lesson from the "sign of Jonah." Perhaps God is nudging you to change something in your life. From time to time, perhaps a certain thought runs through your mind, sort of an inkling to do something (or stop doing something). You shy away from it, slough it off and figure it's just one of those odd thoughts or daydreams.
But maybe it didn't come from you. Maybe it came from the Lord. That makes a difference.
Now, a week into Lent, you may want to take a long look at this. If the Lord is nudging you toward something, you ought to do it.
- Little Black Book, Diocese of Saginaw