כִּ֥י רָ֘דַ֤ף אוֹיֵ֨ב ׀ נַפְשִׁ֗י דִּכָּ֣א לָ֭אָרֶץ חַיָּתִ֑י הוֹשִׁיבַ֥נִי בְ֝מַחֲשַׁכִּ֗ים כְּמֵתֵ֥י עוֹלָֽם׃
For the enemy hath persecuted my soul; He hath crushed my life down to the ground; He hath made me to dwell in darkness, as those that have been long dead.
Read kabbalistic (mystical) interpretation of Psalms 143:3: and classical mystical sources.