Some of the Pharisees that were there told Jesus that they want to see a sign.
Jesus’ response is to say that a wicked generation wants a sign! The only sign given to them is that of the prophet Jonah. Because as Jonah was in the fish for three days and three nights, so the Son of Man will be in the earth for three days and three nights. The people of Nineveh will stand at judgment and condemn this generation because as Jonah preached they repented. This generation has someone greater than Jonah and Solomon and will not listen.
Jesus continues by saying as an evil spirit is driven out it just goes around with nowhere else to go. It finally decides to go back to the person it was cast from, but it seems cleaned up and swept out. So the spirit will bring seven other spirits and they will occupy the person again. This time, leaving the condition of the person worse than it was before. Jesus says this is how this generation will be.
Jesus gives them the ultimate sign. He tells them what will come. He compares His death, burial, and resurrection to Jonah being in the fish. However, to me the comparison that is more significant here is comparing this generation to those of Nineveh. He’s trying to tell the crowd that they need to recognize who speaks before them and repent as Nineveh did. Sometimes we also need to recognize what we have been choosing to follow and listen to. Jesus’ message is to repent and turn to Him. So let’s do just that…repent today and turn back to Him.
A Journey With Jesus 