Matthew 16:1, 6, 12

Then the Pharisees and Sadducees came, and testing Him asked that He would show them a sign from heaven.

Then Jesus said to them, “Take heed and beware of the leaven of the Pharisees and the Sadducees.”

Then they understood that He did not tell them to beware of the leaven of bread, but of the doctrine of the Pharisees and Sadducees.