John 15:12

15:12 My commandment is this – to love one another just as I have loved you.

Mark 8:17-18

8:17 When he learned of this, Jesus said to them, “Why are you arguing about having no bread? Do you still not see or understand? Have your hearts been hardened? 8:18 Though you have eyes, don’t you see? And though you have ears, can’t you hear? Don’t you remember?

Mark 9:19

9:19 He answered them, “You unbelieving generation! How much longer must I be with you? How much longer must I endure you? Bring him to me.”

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.