Matthew 13:47-50
47 Jesus also said, ‘I can tell you again what the kingdom of heaven is like. Some men had nets to catch fish in. They threw their nets into the lake and they caught many different kinds of fish. 48 When the net was full of fish, the men pulled it up onto the shore. Then they sat down. Some of the fish were good to eat, and they put these fish into baskets. Some of the fish were not good to eat, and they threw these fish away. 49 This is what will happen when the world's time comes to an end. God will send his angels. They will put wicked people in one place. And they will put God's righteous people in a separate place. 50 The angels will throw the wicked people into the great fire. There those people will weep and they will bite their teeth together.’
13:50Biting their teeth together may have shown that they were angry. Or it may have shown they were in much pain.