Mark 8:14

11 And the Pharisees came forth, and began to question with him, seeking of him a sign from heaven, tempting him.

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.

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.

15 And he charged them, saying, Take heed, beware of the leaven of the Pharisees, and of the leaven of Herod.

16 And they reasoned among themselves, saying, It is because we have no bread.

17 And when Jesus knew it, he saith unto them, Why reason ye, because ye have no bread? perceive ye not yet, neither understand? have ye your heart yet hardened?