The Peace of God
Be careful for nothing; but in every thing by prayer and supplication with thanksgiving let your requests be made known unto God.
And the peace of God, which passeth all understanding, shall keep [guard] your hearts and minds through Christ Jesus.
The peace of God is part of the spiritual package given to us when we believed in the Lord Jesus Christ and that God raised him from the dead. It becomes manifest as fruit in our lives as we walk by the spirit. The peace of God guards our heart. "These things I have spoken unto you, that in me ye might have peace. In the world ye shall have tribulation: but be of good cheer; I have overcome the world." John 16:33