Ephesians 4
31 Let all bitterness, wrath, anger, clamor, and evil speaking be put away from you, with all malice. 32 And be kind to one another, tenderhearted, forgiving one another, even as God in Christ forgave you.

So chapter four ends the way it starts, with a call to unity.

From my commentary:
The new man seeks to show the same kindness, tender heartedness and forgiveness to others that God shows him. If we treat others as God treats us, we fulfill every thing Paul told us to do in this chapter.

Paul just painted a picture in chapter 4 of a mature Christian.

Put all these into practice.