Provisions are made in Scripture for the avenger of blood. The avenger of blood was the next of kin of the person who had been killed. The avenger of blood was the one to punish the offender.

Reminds me of the revenge attitude of so many people today. "I don't get back, I get even."

Jesus was very clear how He felt about that kind of attitude.
Matt 5:38-39
You have heard that it was said, 'Eye for eye, and tooth for tooth.'39 But I tell you, Do not resist an evil person. If someone strikes you on the right cheek, turn to him the other also.

If we have an attitude of revenge in our hearts, we are following the crowd in doing wrong like we have been warned about before. It's so much easier to follow the crowd than to stand out in a crowd. But as Christians we are called to be different and to stand out!