Matthew 16:12 KJV
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.
Matthew 16:12, King James Version
In context
11 How is it that ye do not understand that I spake it not to you concerning bread, that ye should beware of the leaven of the Pharisees and of the Sadducees?
12 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.
13 When Jesus came into the coasts of Cesarea Philippi, he asked his disciples, saying, Whom do men say that I the Son of man am?