NET
12 Then they understood that he had not told them to be on guard against the yeast in bread, but against the teaching of the Pharisees and Sadducees.
Darby
12 Then they comprehended that he did not speak of being beware of the leaven of bread, but of the doctrine of the Pharisees and Sadducees.
KJV
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.