Mark 8:14

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

12 And he sighed deeply in his spirit, and saith, Why doth this generation seek a sign? verily I say unto you, There shall no sign be given unto this generation.

13 And he left them, and again entering into [the boat] departed to the other side.

14 And they forgot to take bread; and they had not in the boat with them more than one loaf.

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

16 And they reasoned one with another, saying, We have no bread.

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