In order to understand biblical instructions such as this one, we must distinguish between the public law sphere and the private sphere of life. Think of Jonathan’s reaction when Saul, his father, verbally assaulted him: “You son of a perverse and rebellious woman! Don't I know that you have sided with the son of Jesse to your own shame and to the shame of the mother who bore you?” (1 Samuel 20:30).
Jonathan made no reply to his father’s insults. Rather, he replied, “Why should [David] be put to death? What has he done?” (1 Samuel 20:32). Jonathan was willing to bear the injustice done against him by his father. But he stood up for public justice for his friend David.
God has given us judges and legal systems for a reason. We can plead our case with them. Jesus also called for public justice for himself when he said to the authorities, “If I said something wrong, testify as to what is wrong. But if I spoke the truth, why did you strike me?” (John 8:23).
But in private matters (matters that do not concern justice for all), Jesus tells us, “If someone strikes you on the right cheek, turn to him the other also” (Matthew 5:39). In our personal lives we must hold back our anger and bear injustice. We must not take justice out of the hands of God and out of the hands of the judges that he appointed. As this proverb teaches us, we must never say, “I'll do to him as he has done to me; I'll pay that man back for what he did.”
Even though Jonathan and Jesus himself were let down by the public justice systems, there is one final Judge who will not let public or private injustice go unpunished. Be still and wait on him (Psalm 37:7).
29 Do not say, “I will do to him as he has done to me; I will pay the man back for what he has done.”