Isaiah 26:3

You will keep him in perfect peace, whose mind is stayed on You, because he trusts in You.

God is the rewarder of faith.  We stay in faith when we cast down the thoughts that the enemy tries to put in and replace them with the word.  Our faith will be rewarded with perfect peace because we don’t let our minds be troubled.  Faith believes what God says it can do and speaks what God says and peace is a result.