Verses with the word dull in the New Testament (3 verses):

Matthew 13:15
For this people's heart is waxed gross, and their ears are dull of hearing, and their eyes they have closed; lest at any time they should see with their eyes and hear with their ears, and should understand with their heart, and should be converted, and I should heal them.

Acts 28:27
For the heart of this people is waxed gross, and their ears are dull of hearing, and their eyes have they closed; lest they should see with their eyes, and hear with their ears, and understand with their heart, and should be converted, and I should heal them.

Hebrews 5:11
Of whom we have many things to say, and hard to be uttered, seeing ye are dull of hearing.