See also Mark 8:11-12.
The Pharisees also, and the Sadducees - See the notes at Matthew 3:7.
Tempting - That is, trying him - feigning a desire to see evidence that he was the Messiah, but with a real desire to see him make the attempt to work a miracle and fail, so that they might betray him and ruin him.
A sign from heaven - Some miraculous appearance in the sky. Such appearances had been given by the prophets; and they supposed, if he was the Messiah, that his miracles would not all be confined to the earth, but that he was able to give some signal miracle from heaven. Samuel had caused it to thunder 1 Samuel 12:16-18; Isaiah had caused the shadow to go back ten degrees on the dial of Ahaz Isaiah 38:8; and Moses had sent manna from heaven, Exodus 16:4; John 6:31. It is proper to say, that though Christ did not choose then to show such wonders, yet far more stupendous signs from heaven than these were exhibited at his death.
He answered ... - The meaning of this answer is, There are certain indications by which you judge about the weather.
In the evening you think you can predict the weather tomorrow. You have evidence in the redness of the sky by which you judge. So there are sufficient indications on which you should judge concerning me and these times. My miracles, and the state of affairs in Judea, are an indication by which you should judge.
Is red - Almost all nations have observed this as an indication of fair weather.
In the morning ...the sky is red and lowering - That is, there are threatening clouds in the sky, which are made red by the rays of the rising sun. This, in Judea, was a sign of a tempest. In other places, however, the signs of a storm may be different.
The face of the sky - The appearance of the sky.
A wicked and adulterous generation ... - See the notes at Matthew 12:38-40. Mark adds Mark 8:12 that he signed deeply in spirit. He did not say this without feeling; he was greatly affected with their perverseness and obstinacy.