Albert Barnes Commentary Psalms 91:3

"For he will deliver thee from the snare of the fowler, And from the deadly pestilence." — Psalms 91:3 (ASV)

Surely he will deliver you from the snare of the fowler - The snare or trap set for catching birds; meaning, here, that God will save you from the purposes of wicked people; such purposes can be compared to the devices used to catch birds. On the meaning of the figure used here, see the notes at (Psalms 18:5).

And from the noisome pestilence - The fatal pestilence; the pestilence that spreads death in its march. That is, he can prevent its coming upon you, or he can save you from its ravages while others are dying around you. This promise is not to be understood as absolute, or as meaning that no one who fears God will ever die from the pestilence—for good people do die at such times as well as bad people.

But the idea is that God can preserve us at such a time, and that, as a great law, he will thus be the protector of those who trust him. It is to be remembered that in times of pestilence (as was the case during the prevalence of the Asiatic cholera in 1832 and 1848), very many of the victims are the intemperate, the sensual, and the debased, and that a life of this kind is a predisposing cause of death in such visitations of judgment.

A large part of those who die are of that number. From the danger arising from this cause, of course, the virtuous, the temperate, and the pious are exempt; and this is one of the methods by which God saves those who trust in him from the “noisome pestilence.”

Religion, therefore, to a considerable extent, constitutes a ground of security at such times; nor is there any reason to doubt that, in many cases also, there may be a special interposition protecting the friends of God from danger and sparing them for future usefulness. The promise here is substantially that general promise which we have in the Scriptures everywhere, that God is the Protector of his people, and that they may put their trust in him.