The Pharisees and Sadducees ask that He would show them a sign from heaven.
Jesus says no sign will be given to them but the sign of Jonah.
But what is ridiculous is Jesus had been doing tons of signs and miracles in the multitudes of people that came to Him. Did they not see it? Instead of acknowledging all that He had done they chose to ignore the miracles. They didn't really want to believe. If they did their hearts would be soft an their eyes would have been open to what He had done already.
Application: don't forget what Jesus has done in my life. Remember it and stand on it. Be assured in it.
He is not a genie He is my King so treat Him with such honor.