Commentaries:
His use of "heart" reveals that the peace in which He is involved while we are in this world is a state of mind. John 16:33 confirms this: "These things I have spoken to you, that in Me you may have peace. In the world you will have tribulation; but be of good cheer, I have overcome the world."
John W. Ritenbaugh
The Fruit of the Spirit: Peace
God's peace is a deep, spiritual peace unaffected by the world (Romans 8:6-9). We can have this peace, if we truly trust in God's redemptive plan for mankind, are striving to produce His character and are obedient to His Word.
Martin G. Collins
Peace