Isaiah 26:3 in the King James Version
Thou wilt keep him in perfect peace, whose mind is stayed on thee: because he trusteth in thee.
Context
2 Open the gates, that the righteous nation may enter: the one which keeps faith.
3 You will keep whoever’s mind is steadfast in perfect peace, because he trusts in you.
4 Trust in the LORD forever; for in the LORD, the LORD, is an everlasting Rock.