Isaiah 26:3 Kabbalah

יֵ֣צֶר סָמ֔וּךְ תִּצֹּ֖ר שָׁל֣וֹם ׀ שָׁל֑וֹם כִּ֥י בְךָ֖ בָּטֽוּחַ׃

The mind stayed on Thee Thou keepest in perfect peace; Because it trusteth in Thee.

Read kabbalistic (mystical) interpretation of Isaiah 26:3: and classical mystical sources.