Matthew 16:11-12

11 How is it that you fail to perceive that I did not speak about bread? Beware of the leaven of the Pharisees and Sad'ducees."
12 Then they understood that he did not tell them to beware of the leaven of bread, but of the teaching of the Pharisees and Sad'ducees.

Matthew 16:11-12 In-Context

9 Do you not yet perceive? Do you not remember the five loaves of the five thousand, and how many baskets you gathered?
10 Or the seven loaves of the four thousand, and how many baskets you gathered?
11 How is it that you fail to perceive that I did not speak about bread? Beware of the leaven of the Pharisees and Sad'ducees."
12 Then they understood that he did not tell them to beware of the leaven of bread, but of the teaching of the Pharisees and Sad'ducees.
13 Now when Jesus came into the district of Caesare'a Philip'pi, he asked his disciples, "Who do men say that the Son of man is?"
14 And they said, "Some say John the Baptist, others say Eli'jah, and others Jeremiah or one of the prophets."
Revised Standard Version of the Bible, copyright 1952 [2nd edition, 1971] by the Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.