5 Later, after they crossed to the other side of the lake, the disciples discovered they had forgotten to bring any bread. 6 "Watch out!" Jesus warned them. "Beware of the yeast of the Pharisees and Sadducees." 7 At this they began to argue with each other because they hadn't brought any bread. 8 Jesus knew what they were saying, so he said, "You have so little faith! Why are you arguing with each other about having no bread? 9 Don't you understand even yet? Don't you remember the 5,000 I fed with five loaves, and the baskets of leftovers you picked up? 10 Or the 4,000 I fed with seven loaves, and the large baskets of leftovers you picked up? 11 Why can't you understand that I'm not talking about bread? So again I say, 'Beware of the yeast of the Pharisees and Sadducees.'" 12 Then at last they understood that he wasn't speaking about the yeast in bread, but about the deceptive teaching of the Pharisees and Sadducees.
Matthew Henry's Commentary on Matthew 16:5-12
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.