Ps 40:3

“We can call the members of our own bodies our beds, in which our souls repose so delightfully as if in a bed. I think that is what the holy prophet had in mind when he says: "You have turned his whole bed in his sickness." Blessed is he whose bed the Lord turns in his sickness in order that he who not long ago was prone to anger, an adulterer, wanton and full of every sin due to his weaknesses, becomes chaste, humble and modest when the Lord turns a body which was accustomed to evil.”

“"The Lord help him" [Psalm 41:3]. But when? Haply in heaven, haply in the life eternal, that so it remain to worship the devil for earthly needs, for the necessities of this life. Far be it! You have "promise of the life that now is, and of that which is to come." [1 Timothy 4:8] He came unto you on earth, by Whom were made heaven and earth. Consider then what He says, "The Lord help him, on his bed of pain." The bed of pain is the infirmity of the flesh; lest you should say, I cannot hold, and carry, and tie up my flesh; you are aided that you may. The Lord help you on your bed of pain. Your bed did carry you, you carried not your bed, but wast a paralytic inwardly; He comes who says to you, "Take up your bed, and go your way into your house." [Mark 2:11] "The Lord help him on his bed of pain." Then to the Lord Himself He turns, as though it were asked, Why then, since the Lord helps us, suffer we such great ills in this life, such great scandals, such great labours, such disquiet from the flesh and the world? He turns to God, and as though explaining to us the counsel of His healing, He says, "You have turned all his bed in his infirmity." By the bed is understood anything earthly. Every soul that is infirm in this life seeks for itself somewhat whereon to rest, because intensity of labour, and of the soul extended toward God, it can hardly endure perpetually, somewhat it seeks on earth whereon to rest, and in a manner with a kind of pausing to recline, as are those things which innocent ones love....The innocent man rests in his house, his family, his wife, his children; in his poverty, his little farm, his orchard planted with his own hand, in some building fabricated with his own study; in these rest the innocent. But yet God willing us not to have love but of life eternal, even with these, though innocent delights, mixes bitterness, that even in these we may suffer tribulation, and so He turns all our bed in our infirmity. "You have turned all his bed in his infirmity." Let him not then complain, when in these things which he has innocently, he suffers some tribulations. He is taught to love the better, by the bitterness of the worse; lest going a traveller to his country, he choose the inn instead of his own home.”

“May the Lord help him. That even in the present time the truth of these prophetic promises may be found. Many, laboring in sickness and disease, when they leave behind their own poor and needy works, are changed for the better. For if even on a future day judgment triumphs over mercy, what a marvel it would be, if also he would turn away by his rich mercy the death which we await, and he would restore strength? Surely this is the frailty of spirit, which is received in the inner man, wherein he has determined hands or the strength to do things. Even crippled knees are healed that were not strong before to walk on the way to life. Then the mercy bequeathed to the poor heals and revives the spirit held back by its grave disease of folly and brought to death from its sin. He, therefore, immediately added: "I said: Lord, have mercy on me, heal my soul, because I have sinned against you."”

“"The Lord bring him aid." Here is set forth a prayer for the merciful person in adversity. And first he asks for divine help or support; second he alleges the necessity of this. He says therefore, "The Lord bring him aid upon his bed of sorrow." He prays for the merciful person, or for the just man, a son of Korah simply, that the Lord give him life and make him blessed upon the earth. Second, that he preserve him and not deliver him into the souls of his enemies. And from this someone could infer that the merciful person would in no way be afflicted. Hence, to exclude this, he says that sometimes his bed is filled with sorrows, and this happens to the merciful person sometimes for correction. Job 33: "He rebukes sometimes through pain on the bed." Or for humiliation, as the thorn of the flesh was given to Paul, 2 Cor. 12. Or for testing, as in Job throughout, and in Tobit. And therefore he says, "The Lord bring him aid," that is, the merciful person in tribulation, "upon the bed," literally on which he lies, or on which he rests. 1 Cor. 10: "God is faithful, who will not allow you to be tempted beyond what you can bear." And that you bring him aid, a great necessity demands this, because "You have turned all his bed in his sickness." And he speaks here after the likeness of one with a fever, who finds no place on the bed where he can rest, but continually turns himself. And therefore he says, "You have turned"; as if to say: he needs aid because his infirmity is so great that he is continually turned about in bed. And this is according to the literal sense; yet simply everything through which he found rest in temporal things has been turned to bitterness for him, because God places bitterness in them, so that, having despised them, one may be converted to God. Eccl. 2: "And when I turned to all the works which my hands had wrought, I saw in all things vanity."”