The Pharisees and other Jewish leaders approached Jesus with a test, asking him to show them a sign from heaven.
He sighed deeply and said “You know how to read the signs in the sky. When the sky is red at night, you know there will be good weather the next day, and when the sky is red in the morning you know there will be storms. Yet you don’t know how to read the signs of the times! Why does this wicked generation demand to see a sign? It will see nothing except the sign of Jonah.” He walked away from them, got back on the boat, and went to the other side of the sea.
When they reached the other side, the disciples realized that they had forgotten to get more bread. They had only one loaf with them. Jesus said “Beware of the yeast of the Pharisees.” They began to talk among themselves about the fact that they didn’t have any more bread.
Jesus was aware of this and he said “Why are you talking about not having any more bread? Don’t you understand yet? Do you have eyes and ears and yet are blind and deaf? Don’t you remember how five loaves of bread were able to feed 5000 people, or that seven loaves of bread fed 4000 people? Remember the number of large baskets of leftover pieces? Why do you not understand that when I said ‘Beware the yeast of the Pharisees,’ I wasn’t talking about bread?”
Then they understood that he was talking about what the Pharisees taught.
MT 16:1-12, MK 8:11-21