In the Shin/Sin section of Psalm 119, that is verses 161-168, we find a subtle shift of mood and tone. The psalmist is resolute and determined, but now a tranquility and peace hangs over the psalm. He’s peacefully resolve to …
Tremble at the word. And what a contrast in the opening lines of this section (v. 161): “Rulers” may persecute me without cause, but my heart trembles at your word.
Who knows who those rulers were — they were chiefs or princes or captains. Someone with power, someone who could persecute the psalmist. Think some significant, powerful leader who abuses his power to overwhelm the pious.

And when those rulers are staring him down, the psalmist finds repose, rest, tranquility, and peace — because he does not fear them. He fears God.
His heart stands in awe of God’s words. The word “stands in awe” is sometimest translated “dread.” Once again, a subtle deconstruction of his opponents: he does not fear their power; he dreads the quiet word of God.