“And the Pharisees came forth, and began to question with Him, seeking of Him a sign from heaven, tempting Him. 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.’
And He left them, and entering into the ship again departed to the other side.”  Mark 8:11-13  (KJB)