The Pharisees and Sadducees approached, and tested him, asking him to show them a sign from heaven. He replied, “When evening comes you say, ‘It will be good weather because the sky is red.’ And in the morning, ‘Today will be stormy because the sky is red and threatening.’ You know how to read the appearance of the sky, but you can’t read the signs of the times. An evil and adulterous generation demands a sign, but no sign will be given to it except the sign of Jonah.” Then he left them and went away.
The disciples reached the other shore, and they had forgotten to take bread. Then Jesus told them, “Watch out and beware of the leaven of the Pharisees and Sadducees.”
They were discussing among themselves, “We didn’t bring any bread.”
Aware of this, Jesus said, “You of little faith, why are you discussing among yourselves that you do not have bread? Don’t you understand yet? Don’t you remember the five loaves for the five thousand and how many baskets you collected? Or the seven loaves for the four thousand and how many large baskets you collected? Why is it you don’t understand that when I told you, ‘Beware of the leaven of the Pharisees and Sadducees,’ it wasn’t about bread?” Then they understood that he had not told them to beware of the leaven in bread, but of the teaching of the Pharisees and Sadducees.