But the children of the murderers he slew not: according unto that which is written in the book of the law of Moses, wherein the LORD commanded, saying, The fathers shall not be put to death for the children, nor the children be put to death for the fathers; but every man shall be put to death for his own sin.
But he didn't kill the children of murderers. This is based on a rule in Moses' law book, where the LORD said that parents shouldn't be punished for their children's actions and vice versa; each person is responsible for their own wrongdoing.