An evil and adulterous generation seeks for a sign, and a sign will not be given to it except the sign of Jonah!" And he left them [and] went away. And [when] the disciples arrived at the other side, they had forgotten to take bread. And Jesus said to them, "Watch out for and beware of the leaven of the Pharisees and Sadducees!" read more.
So they were discussing [this] among themselves, saying, "[It is] because we did not take bread." But knowing [this], Jesus said, "Why are you discussing among yourselves that you did not take bread, [you] of little faith? Do you not yet understand or do you not remember the five loaves for the five thousand, and how many baskets you took up? Or the seven loaves for the four thousand and how many baskets you took up? How do you not understand that I did not speak to you about bread? But beware of the leaven of the Pharisees and Sadducees!" Then they understood that he did not say to beware of the leaven of bread, but of the teaching of the Pharisees and Sadducees.

And he left them, got into [the boat] again, [and] went to the other side. And they had forgotten to take bread, and except [for] one loaf, they did not have [any] with them in the boat. And he ordered them, saying, "Watch out! Beware of the leaven of the Pharisees and the leaven of Herod!" read more.
And they began to discuss with one another that they had no bread. And knowing [this], he said to them, "Why are you discussing that you have no bread? Do you not yet perceive or understand? Have your hearts been hardened? [Although you] have eyes, do you not see? And [although you] have ears, do you not hear? And do you not remember? When I broke the five loaves for the five thousand how many baskets full of broken pieces did you pick up?" They said to him, "Twelve." "When also [broke] the seven [loaves] for the four thousand, how many baskets full of broken pieces did you pick up?" And they said to him, "Seven." And he said to them, "Do you not yet understand?"