You keep him in perfect peace whose mind is stayed on you, because he trusts in you.
From whom shall we receive peace?
John 14:27 ESV
Peace I leave with you; my peace I give to you. Not as the world gives do I give to you. Let not your hearts be troubled, neither let them be afraid.
How does our faith give us peace?
Romans 5:1 ESV
Therefore, since we have been justified by faith, we have peace with God through our Lord Jesus Christ.
We are not at peace with others because we are not at peace with ourselves, and we are not at peace with ourselves because we are not at peace with God.