James 5:15 - Matthew Poole's English Annotations on the Holy Bible

And the prayer of faith; i.e. proceeding from faith; the cure is ascribed to prayer, the moral means, and standing ordinance, not to the anointing, which was but ceremonial and temporary; and to faith in prayer, to show that this remedy was effectual only when faith (requisite to the working of miracles) was active, viz. in a certain persuasion that the sick person should be healed. Shall save the sick; restore to health, (if God see it fit, and the health of the body be good for the soul), Mark 10:52 Luke 7:50, Luke 18:42. And the Lord shall raise him up; the elders pray, but the Lord raiseth up, being prayed to in faith. Raise him up; the same as saving before, only the word seems to respect the sick man's lying upon his bed, from which he riseth when he is healed, Mark 1:31. If he have committed sins; if he have by his sins procured his sickness; or, those sins for which particularly God visits him with sickness; sin being often the cause of sickness, Matthew 9:2 1 Thessalonians 5:14 1 Corinthians 11:30, though not always, 1 Thessalonians 9:2. They shall be forgiven him; God will take away the cause as well as the effect, heal the soul as well as the body, and prayer is the means of obtaining both.