Here is a good exposition of this Psalm from "The Believer's Bible Commentary":
91:1, 2 Jesus is the One who in a preeminent way dwelt in the secret place of the Most High, and abode under the shadow of the Almighty. There never was a life like His. He lived in absolute, unbroken fellowship with God, His Father. He never acted in self-will but did only those things that the Father directed. He lived His life in utter and complete dependence on God. Without equivocation He could look up and say, "My refuge and my fortress, my God, in Him I will trust."
91:3 God's voice is heard in verses 3-13, assuring the Lord Jesus of the tremendous security that was His because of His life of perfect trust. What are the guarantees of security? There are nine:
Deliverance from hidden dangers. The snare of the bird-trapper speaks of the enemy's evil plot to trap the unwary.
Immunity from fatal disease. In our Lord's case, there is no reason to believe that He was ever sick at all.
91:4 Shelter and refuge in the Almighty. God's tender, personal care is likened to that of a mother bird with her young.
Protection in the faithfulness of God. His promises are sure. What He has said, He will do. This is the believer's shield and buckler.
91:5 Freedom from fear. Four types of danger are mentioned that commonly cause apprehension:
Attacks made by an enemy under the cover of night are especially terrifying because the source is hard to identify.
The arrow that flies by day may be understood as a literal missile or as a figure for "the evil plots and slanders of the wicked" (Amplified Version).
91:6 The pestilence that walks in darkness may also be taken literally or figuratively. Physical disease thrives where it is shielded from the sun's rays, and moral evil also breeds in the dark.
The destruction that lays waste at noonday is unspecified, and perhaps it is best to leave it that way, so that the promise may have a more widespread application.
91:7, 8 Safety even in the midst of massacre. Even where there is slaughter on a wholesale basis, the Beloved of the Lord is absolutely safe. When the wicked are punished, He will be a spectator only, free from the possibility of harm.
91:9, 10 Insurance against calamity. Because the Savior made the Most High His refuge and His dwelling place, no disaster would strike Him, no calamity would get near Him.
91:11, 12 Guarded by angelic escort. This is the passage which Satan quoted to the Lord Jesus when tempting Him to throw Himself down from the pinnacle of the temple (Luk_4:10-11). Jesus did not deny that the verses applied to Him, but He did deny that they could be used as a pretext for tempting God. God had not told Him to jump down from the temple. If the Savior had jumped, He would have been acting outside the divine will, and then the promise of protection would not have been valid.
91:13 Victory over the lion and cobra. It is interesting that Satan stopped before coming to this verse. If he had quoted it, he would have been describing his own doom! The devil is presented in Scripture as a roaring lion (1Pe_5:8) and as an ancient serpent (Rev_12:9). As a lion, he is the loud, horrendous persecutor using physical violence. As a serpent, he employs wily stratagems to deceive and to destroy. This is the "mind of the flesh" which is enmity against God.
And so the Holy Spirit has given nine guarantees of safe-conduct to the Son of Man during His life of perfect trust and obedience on earth. At this point God the Father confirms the guarantees by six tremendous "I wills." In these perhaps there is a suggestion of the entire career of the Lord Jesus:
91:14 His spotless life. "Because he has set his love upon Me, therefore I will deliver him; I will set him on high, because he has known My name."
91:15 His suffering because of sin. "He shall call upon Me, and I will answer him; I will be with him in trouble."
His resurrection and ascension. "I will deliver him and honor him."
91:16 His present session at God's right hand and His coming kingdom. "With long life I will satisfy him, and show him My salvation."
So much for what the Psalm says! But wait! You are probably thinking of what it does not say, of important questions that it does not answer. For example, how can we reconcile all these promises of safe-keeping for the Messiah with the fact that men ultimately did put Him to death? And if we apply the Psalm to believers today, how does it square with the fact that some of them do succumb to disease, or fall in battle, or die in plane crashes?
Part of the answer, at least, lies in this: The one who trusts in Yahweh is immortal until his work is done. Jesus said as much to His disciples. When He suggested returning to Judea, the disciples said:
"Rabbi, lately the Jews sought to stone You, and are You going there again?" Jesus answered, "Are there not twelve hours in the day? If anyone walks in the day, he does not stumble, because he sees the light of this world. But if one walks in the night, he stumbles, because the light is not in him" (John 11:7-10).
The Lord knew that the Jews could not touch Him until He had finished His work. And this is true of every true believer; he is kept by the power of God through faith.
Finally, it is true in a general way that those who trust the Lord are sure of His protection. We may tend to overemphasize the exceptions. The general rule is still true: there is safety in the Lord.
I hope you have found this helpful,
God bless and keep you,