"Take heed and beware of the leaven of the Pharisees and of the Sadducees" Matthew 16:6. This was the admonition the disciples received from Jesus upon crossing the lake. "And they reasoned among themselves, saying, It is because we have taken no bread" verse 7. They had really missed the boat, so to speak. There are certainly times we are rather dense in our understanding of spiritual matters. After Jesus' clarification," Then understood they how that he bade them not beware of the leaven of bread, but of the doctrine of the Pharisees and of the Sadducees" verse 12.