Matthew 16:1-3

Now the Pharisees and Sadducees came up, and testing Jesus [to get something to use against Him], they asked Him to show them a sign from heaven [which would support His divine authority]. But He replied to them, “When it is evening, you say, ‘It will be fair weather, for the sky is red.’ And in the morning, ‘It will be stormy today, for the sky is red and has a threatening look.’ You know how to interpret the appearance of the sky, but cannot interpret the signs of the times?