Passage
You shall not be afraid of the terror by night, nor of the arrow that flies by day;
You shall not be afraid of the terror by night, nor of the arrow that flies by day;
Psalms 91:3 For he will deliver you from the snare of the fowler, and from the deadly pestilence.
Psalms 91:4 He will cover you with his feathers. Under his wings you will take refuge. His faithfulness is your shield and rampart.
Psalms 91:5 You shall not be afraid of the terror by night, nor of the arrow that flies by day;
Psalms 91:6 nor of the pestilence that walks in darkness, nor of the destruction that wastes at noonday.
Psalms 91:7 A thousand may fall at your side, and ten thousand at your right hand; but it will not come near you.
The verse centers on "shall", "afraid", "terror", "night", "arrow", and "flies". It is saying that the verse draws attention to "shall" and "afraid", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 4's "He will cover you with his feathers..." into verse 6's "nor of the pestilence that walks in...", so "shall" and "afraid" belong inside that flow. In Psalms context, the local focus is worship, trust, the LORD's kingship, and covenant mercy.
A plain takeaway is to answer the verse's own emphasis on "shall" and "afraid" with trust shaped by these words, not by a vague optimism outside the passage.