6 Then Jesus said to them, "Take heed and beware of the leaven of the Pharisees and the Sadducees." 7 And they reasoned among themselves, saying, "It is because we have taken no bread." 8 But Jesus, being aware of it, said to them, "O you of little faith, why do you reason among yourselves because you have brought no bread? 9 Do you not yet understand, or remember the five loaves of the five thousand and how many baskets you took up? 10 Nor the seven loaves of the four thousand and how many large baskets you took up? 11 How is it you do not understand that I did not speak to you concerning bread?--but to beware of the leaven of the Pharisees and Sadducees." 12 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.
Matthew Henry's Commentary on Matthew 16:6-12
Commentary on Matthew 16:5-12
(Read Matthew 16:5-12)
Christ speaks of spiritual things under a similitude, and the disciples misunderstand him of carnal things. He took it ill that they should think him as thoughtful about bread as they were; that they should be so little acquainted with his way of preaching. Then understood they what he meant. Christ teaches by the Spirit of wisdom in the heart, opening the understanding to the Spirit of revelation in the word.