"But the house of Israel is not willing to listen to you because they are not willing to listen to me, for the whole house of Israel is hardened and obstinate." NIV translation
God explains that the people are not going to listen to Ezekiel because of the fact that their hearts are not open to hearing. The words may enter their ears but they will not penetrate the stubborn heart. This is also what Jesus was talking about in the letters to the churches when He said "He who has an ear to hear, let him hear" (see Revelation 2). The same is true today as many people may hear the good news that Jesus has paid for their sins but they do not let the words penetrate to their hearts and change them.
God continues to tell Ezekiel of how he is going to be used. Here, we see that God is going to make the prophet stand firm even though the people do not want to listen. This is speaking of patience which is one of the "fruits of the Spirit" that Paul talked about in Galatians 5. Just as God said that He was going to do this in the prophet, we can be assured that God will do the same in us through the Holy Spirit.
Today, there are many that do not want to hear about the things of God but we, like Ezekiel, must be unyielding in our proclamation of the very Word of God. God said that He would make his head harder than flint which is a rock that is so hard that it is used to create a spark and a fire. May God make us so steadfast in His Word that it causes a fire in hearts around the world.
"And he said to me, 'Son of man, listen carefully and take to heart all the words I speak to you. Go now to your countrymen in exile and speak to them. Say to them, "This is what the Sovereign Lord says," whether they listen or fail to listen.'" NIV translation
Ezekiel has received his instructions and been reassured that God is with him. Now, he is told to go to those who are in exile and declare the Word of the Lord. This is just like what happened before Jesus was taken up to heaven. He gave us our instructions, reassured us that He would be with us, and told us to go (see Matthew 28:18-20). We, too, are told to go to those who are in exile as, without Christ, those around us are in captivity.