Proverbs 20:22

Say not thou, I will recompense evil; but wait on the LORD, and he shall save thee.

Personal revenge is forbidden, so no one is ever justified in repaying evil with evil. The wronged person is not to declare an intention to pay back the injury suffered. Instead the command is to wait on the Lord and trust Him to bring deliverance. He Himself will save the one who refrains from self-avenging and looks to Him.