A wicked and unfaithful generation is asking for a sign, but no sign shall be given it except the sign of Jonah." So he left them and went away. Now the disciples had crossed to the opposite shore, and had forgotten to take any bread. Presently Jesus said to them: "Take care and be on your guard against the leaven of the Pharisees and Sadducees." read more.
But the disciples began talking among themselves about their having brought no bread. On noticing this, Jesus said: "Why are you talking among yourselves about your being short of bread, O men of little faith? Do not you yet see, nor remember the five loaves for the five thousand, and how many baskets you took away? Nor yet the seven loaves for the four thousand, and how many basketfuls you took away? How is it that you do not see that I was not speaking about bread? Be on your guard against the leaven of the Pharisees and Sadducees." Then they understood that he had told them to be on their guard, not against the leaven of bread, but against the teaching of the Pharisees and Sadducees.

So he left them to themselves, and, getting into the boat again, went away to the opposite shore. Now the disciples had forgotten to take any bread with them, one loaf being all that they had in the boat. So Jesus gave them this warning. "Take care," he said, "beware of the leaven of the Pharisees and the leaven of Herod." read more.
They began talking to one another about their being short of bread. And, noticing this, Jesus said to them: "Why are you talking about your being short of bread? Do not you yet see or understand? Are your minds still so slow or comprehension? 'Though you have eyes, do you not see? and though you have ears, do you not hear?' Do not you remember, When I broke up the five loaves for the five thousand, how many baskets of broken pieces you picked up?" "Twelve," they said. And when the seven for the four thousand, how many basketfuls of broken pieces did you pick up?" "Seven," they said. "Do not you understand now?" he repeated.