Many people begin a completely new section here, and there's a certain amount of justification for that, because now it is all about the call to repentance until chapter 4 verse 4. But what has gone before leads up to this challenge to Judah.
People want to say that God judges everyone else but it will not come near them. We have to think in a different way. If we are guilty of doing the same thing, why should God not judge us in the same way. After all, we know that his judgments on one are a warning to another. This is the point about the symbolic proportion of a third in Revelation 8. Similarly Christ used the judgment on some to warn others and cautioned them not to think falsely that it had not come to them because they were somehow better (Luke 12:34). It is a dangerous think to try the patience of God.