Matthew 16:1-12

1 Then the Pharisees and Sadducees came, and testing Him asked that He would show them a sign from heaven. 2 He answered and said to them, “When it is evening you say, ‘It will be fair weather, for the sky is red’; 3 and in the morning, ‘It will be foul weather today, for the sky is red and threatening.’ Hypocrites! You know how to discern the face of the sky, but you cannot discern the signs of the times. 4 A wicked and adulterous generation seeks after a sign, and no sign shall be given to it except the sign of the prophet Jonah.” And He left them and departed.
5 Now when His disciples had come to the other side, they had forgotten to take bread. 6 Then Jesus said to them, “Take heed and beware of the leaven of the Pharisees and the Sadducees.” 7 And they reasoned among themselves, saying, “It is because we have taken no bread.” 8 But Jesus, being aware of it, said to them, “O you of little faith, why do you reason among yourselves because you have brought no bread? 9 Do you not yet understand, or remember the five loaves of the five thousand and how many baskets you took up? 10 Nor the seven loaves of the four thousand and how many large baskets you took up? 11 How is it you do not understand that I did not speak to you concerning bread?—but to beware of the leaven of the Pharisees and Sadducees.” 12 Then they understood that He did not tell them to beware of the leaven of bread, but of the doctrine of the Pharisees and Sadducees.
— MATTHEW 16:1-12