Psalm 91 — He who dwells in the shelter of the Most High
Qui habitat (Ps 90/91)
Whoever dwells in the shelter of the Most High abides in the shadow of the Almighty. I say to the Lord: My refuge, my stronghold, my God in whom I trust. He will free you from the snare of the fowler, from the destroying plague. He will cover you with His pinions; under His wings you will find refuge. His faithfulness is buckler and shield. You shall not fear the terror of the night, nor the arrow that flies by day, nor the plague that prowls in the darkness, nor the scourge that lays waste at noon. A thousand may fall at your side, ten thousand fall at your right hand: it will never come near you. Your eyes have only to look to see how the wicked are repaid. Because you have made the Lord your refuge, the Most High your dwelling place, no evil shall befall you, no plague come near your tent. For He has commanded His angels to keep you in all your ways. They shall bear you upon their hands lest you strike your foot against a stone. On the lion and the viper you will tread, and trample the young lion and the dragon. Because he clings to me I will free him; protect him, for he knows my name. When he calls I shall answer: I am with you. I will save him in distress and give him glory. With length of days I will content him; I shall let him see my saving power.
When this prayer is prayed
At Compline every Sunday night, over a house at night, in epidemics, in war, and in exorcisms. It is also the psalm the devil quoted in the desert (Mt 4:6) — which tells you how much it costs him.