Pharisees and Sadducees Seek a Sign

The Pharisees and Sadducees came, and tempting desired Jesus that He would show them a sign from heaven. He answered and said unto them, When it is evening, you say, It will be fair weather: for the sky is red. And in the morning, It will be foul weather today: for the sky is red and lowering. O you hypocrites, you can discern the face of the sky; but you cannot discern the signs of the times? A wicked and adulterous generation seeks after a sign, and there shall no sign be given unto it, but the sign of the prophet Jonas. And he left them and departed. Matthew 16 vs 1-4.