Pharisees (and Sadducees) request a sign from heaven

Mark 8:11 And the Pharisees came forth, and began to question with him, seeking of him a sign from heaven, tempting him. Matt 16:1 The Pharisees also with the Sadducees came, and tempting desired him that he would shew them a sign from heaven.
Mark 8:12 And he sighed deeply in his spirit, and saith, Why doth this generation seek after a sign? verily I say unto you, There shall no sign be given unto this generation. Matt 16:2 He answered and said unto them, When it is evening, ye say, It will be fair weather: for the sky is red. 3 And in the morning, It will be foul weather to day: for the sky is red and lowring. O ye hypocrites, ye can discern the face of the sky; but can ye not discern the signs of the times? 4 A wicked and adulterous generation seeketh 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.
Mark 8:13 And he left them, and entering into the ship again departed to the other side. 14 Now the disciples had forgotten to take bread, neither had they in the ship with them more than one loaf. Matt 16:5 And when his disciples were come to the other side, they had forgotten to take bread.