Mark 3:5

3:5 After looking around at them in anger, grieved by the hardness of their hearts, he said to the man, “Stretch out your hand.” He stretched it out, and his hand was restored.

Mark 6:52

6:52 because they did not understand about the loaves, but their hearts were hardened.

Mark 16:14

16:14 Then he appeared to the eleven themselves, while they were eating, and he rebuked them for their unbelief and hardness of heart, because they did not believe those who had seen him resurrected.

Isaiah 63:17

63:17 Why, Lord, do you make us stray from your ways,

and make our minds stubborn so that we do not obey you?

Return for the sake of your servants,

the tribes of your inheritance!

Matthew 15:17

15:17 Don’t you understand that whatever goes into the mouth enters the stomach and then passes out into the sewer?

Matthew 16:8-9

16:8 When Jesus learned of this, he said, “You who have such little faith! Why are you arguing among yourselves about having no bread? 16:9 Do you still not understand? Don’t you remember the five loaves for the five thousand, and how many baskets you took up?

Luke 24:25

24:25 So he said to them, “You foolish people – how slow of heart to believe all that the prophets have spoken!

Hebrews 5:11-12

The Need to Move on to Maturity

5:11 On this topic we have much to say and it is difficult to explain, since you have become sluggish in hearing. 5:12 For though you should in fact be teachers by this time, you need someone to teach you the beginning elements of God’s utterances. You have gone back to needing milk, not solid food.