2 I will say of the LORD, He is my refuge and my fortress: my God; in him will I trust.
[AD 253] Origen of Alexandria on Psalms 91:1-6
He said these things about the just and wise person and these are said in the blessings, “You will sleep and there will not be anyone who frightens you.” For if I am made just, no one can frighten me; I am afraid of nothing else, if I fear God. For it says, “the just is confident as a lion,” and for this reason, he does not fear the lion, the devil, or “the dragon,” Satan, or “his angels”;16 but, according to David, he says, “I shall not be afraid of the nocturnal fear, nor the dart which flies during the day, nor the terror which walks in the darkness nor the ruin and the midday demon.” And he adds that “the Lord is my light and my Savior, whom shall I fear? The Lord is the defender of my life, at what shall I tremble?” And again, “If an army stands against me, my heart will not fear.” You see the steadfastness and vigor of the soul that keeps the commandments of God and has confidence in the freedom that God gives.

[AD 395] Gregory of Nyssa on Psalms 91:1-6
When the great David heard and understood this, he [David] said to him “who dwells in the shelter of the most High; He will overshadow you with his shoulders,” which is the same as being behind God (for the shoulder is on the back of the body). Concerning himself David says, “My soul clings close to you, your right hand supports me.” You see how Psalms agree with the history. For as the one says that the right hand is a help to the person who has joined himself close behind God, so the other says that the hand touches the person who waits in the rock on the divine voice and prays that he might follow behind.

[AD 420] Jerome on Psalms 91:1-6
“Say to the Lord, ‘My refuge and my fortress, my God.’ ” I am hemmed in by enemies. You, therefore, are my refuge. “ ‘In whom I will trust.’ For he will rescue you from the snare of the hunters.’ ” Note carefully that the psalmist did not say “I trust” but “I will trust.” As long as we continue in a life of sin, we certainly are not trusting; if we put an end to sin, then our hope is confident. “For he will rescue you from the snare of the hunters.” There are many hunters in this world that go about setting traps for our soul. Nimrod the giant was a “mighty hunter before the Lord.” Esau, too, was a hunter, for he was a sinner. In all of holy Scripture, never do we find a hunter that is a faithful servant; we do find faithful fishermen.“For he will rescue you from the snare of the hunters.” “We were rescued like a bird from the fowler’s snare; broken was the snare, and we were freed.” What snare is this that has been broken? “The Lord,” says the apostle, “will speedily crush Satan under our feet”;10 “that you may recover yourselves from the snare of the devil.” You see, then, that the devil is the hunter, eager to lure our souls unto perdition. The devil is master of many snares, deceptions of all kinds. Avarice is one of his pitfalls, disparagement is his noose, fornication is his bait. “And from the destroying word.” As long as we are in the state of grace, our soul is at peace; but once we begin to play with sin, then our soul is in trouble and is like a boat tossed about by the waves.

[AD 420] Jerome on Psalms 91:1-6
“Nor the attack of the noonday demon.” This is better expressed by the Greek. Symptosis implies a chance occurrence when something strange happens unexpectedly; or symptoma may denote a disaster in which many perish at the same time. Grasp, then, what it means. Even though many have been seduced, nevertheless, you who are in the state of grace may escape seduction. I shall give you an example so that even the more simple[-minded] among you may understand what I mean. If you should go to the city, a monk all by yourself, and while you are strolling about you hear a shout in the circus and someone says to you, “Come and see, it is the circus,” and you hold back remonstrating, “I have no permission, I cannot go”; if he should call your attention to the thousands of people there and say to you, “Two hundred thousand people are there, are they all going to be lost, and you alone be saved?” You have to be aware that symptoma is the devil’s own doing. What I am trying to say is that you have to know that many do perish and are lost.

[AD 430] Augustine of Hippo on Psalms 91:1-6
“When the fullness of time had come, God sent his Son, made from a woman, made under the law.” People are upset by “made from a woman,” because we confess that he was born of a virgin. It is only of man that we confess he was made; God is always the one who makes, he cannot be made in order to be. God cannot be made; but he is made into, or becomes, something for someone, in the way in which it is said of him, “Lord, you have become (or have been made into) a refuge for us”; and, “The Lord has become (has been made) my helper.” How many things he has been made into, though he never was made at all! Now the Lord Christ was made man, … in order for him who was always the creator to be a creature. While remaining God, you see, he became man in order to become what he was not, not in order to stop being what he was.

[AD 430] Augustine of Hippo on Psalms 91:1-2
He then who so imitates Christ as to endure all the troubles of this world, with his hopes set upon God, that he falls into no snare, is broken down by no panic fears, he it is "who dwells under the defence of the Most High, who shall abide under the protection of God" [Psalm 91:1], in the words with which the Psalm, which you have heard and sung, begins. You will recognise the words, so well known, in which the devil tempted our Lord, when we come to them. "He shall say unto the Lord, You are my taker up, and my refuge: my God" [Psalm 91:2]. Who speaks thus to the Lord? "He who dwells under the defence of the Most High:" not under his own defence. Who is this? He dwells under the defence of the Most High, who is not proud, like those who ate, that they might become as Gods, and lost the immortality in which they were made. For they chose to dwell under a defence of their own, not under that of the Most High: thus they listened to the suggestions of the serpent, [Genesis 3:5] and despised the precept of God: and discovered at last that what God threatened, not what the devil promised, had come to pass in them.