4 Hear ye all His rewards. “Who forgives all your sin: who heals all your infirmities”. Behold His rewards. What, save punishment, was due unto the sinner? What was due to the blasphemer, but the hell of burning fire? He gave not these rewards: that you may not shudder with dread: and without love fear Him....But you are a sinner. Turn again, and receive these His rewards: He “forgives all your sin.”...Yet even after remission of sins the soul herself is shaken by certain passions; still is she amid the dangers of temptation, still is she pleased with certain suggestions; with some she is not pleased, and sometimes she consents unto some of those with which she is pleased: she is taken. This is infirmity: but He “heals all your infirmities.” All your infirmities shall be healed: fear not. They are great, you will say: but the Physician is greater. No infirmity comes before the Almighty Physician as incurable: only suffer you yourself to be healed: repel not His hands; He knows how to deal with you. Be not only pleased when He cherishes you, but also bear with Him when He uses the knife: bear the pain of the remedy, reflecting on your future health.... You do not endure in uncertainty: He who promised you health, cannot be deceived. The physician is often deceived: and promises health in the human body. Why is he deceived? Because he is not healing his own creature. God made your body, God made your soul. He knows how to restore what He has made, He knows how to fashion again what He has already fashioned: do thou only be patient beneath the Physician's hands: for He hates one who rejects His hands. This does not happen with the hands of a human physician....
5. “Who redeems your life from corruption”. Behold, “the body which is corrupted, weighs down the soul.” The soul then has life in a corruptible body. What sort of life? It suffers burdens, it bears weights. How great obstacles are there to thinking of God Himself, as it is right that men should think of God, as if interrupting us from the necessity of human corruption? How many influences recall us, how many interrupt, how many withdraw the mind when fixed on high? What a crowd of illusions, what tribes of suggestions? All this in the human heart, as it were, teems with the worms of human corruption. We have set forth the greatness of the disease, let us also praise the Physician. Shall not He then heal you, who made you such as to be in health, had you chosen to keep the law of health which you had received?...First think of your own health. Sometimes a man is stricken in his own house, on his bed, with a more than usually manifest disorder; although this disorder too, which men dislike to contemplate, be plain; yet each man may be attacked with that sickness for which human physicians are sought, and may gasp with fever in his bed; perhaps he may wish to consider of his domestic affairs, to make some order or disposition relating to his estate or his house; at once he is recalled from such cares by the anxiety of his friends, plainly expressed around him, and he is advised to dismiss these subjects, and first to take thought for his health. This then is addressed unto you, and to all men: if you are not sick, think of other things: if your very infirmity prove you sick, first take heed of your health. Christ is your health: think therefore of Christ. Receive the cup of His saving Health, “who heals all your infirmities;” if you shall choose, you shall gain this Health....For your life has been redeemed from corruption: rest secure now: the contract of good faith has been entered upon; no man deceives, no man circumvents, no man oppresses, your Redeemer. He has here made a barter, He has already paid the price, He has poured forth His blood. The only Son of God, I say, has shed His blood for us: O soul, raise yourself, you are of so great price....“He redeems your life from corruption.”
6. “Who crowns you with mercy and loving-kindness.” You had perhaps begun to be in a manner proud, when you heard the words, “He crowns you.” I am then great, I have then wrestled. By whose strength? By yours, but supplied by Him....He crowns you, because He is crowning His own gifts, not your deservings. “I laboured more abundantly than they all,” said the Apostle; but see what he adds: “yet not I, but the grace of God which was with me.”...It is then by His mercy that you are crowned; in nothing be proud; ever praise the Lord; forget not all His rewards. It is a reward when thou, a sinner and an ungodly man, hast been called, that you may be justified. It is a reward, when you are raised up and guided, that you may not fall. It is a reward, when strength is given you, that you may persevere unto the end. It is a reward, that even that flesh of yours by which you were oppressed rises again and that not even a hair of your head perishes. It is a reward, that after your resurrection you are crowned. It is a reward, that you may praise God Himself for evermore without ceasing....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)