Following the feeding of the 4000 men, Jesus is asked by some Pharisees to given them a sign from heaven. They wanted to "test" him. He tells them that no sign will be given to them. Afterward, while journeying to the other side of the Sea of Galilee, Jesus begins to charge his disciples, "beware of the yeast of the Pharisees and the yeast of Herod." We delve into what Jesus warned them about and the relevance of his warning in our day.