Albert Barnes Commentary Psalms 41:4

"I said, O Jehovah, have mercy upon me: Heal my soul; for I have sinned against thee." — Psalms 41:4 (ASV)

I said, Lord - I said in my sickness, or in the trial referred to in the psalm. I called on God to be merciful to me when others had no mercy; to be near to me when others turned away; to save me when pressed down with disease on account of my sins. All that follows relates, like this passage, to what occurred when he was sick; to the thoughts that passed through his mind, and to the treatment which he then experienced from others.

Be merciful to me - In forgiving my sins, and restoring me to health.

Heal my soul - In restoring my soul to spiritual health by forgiving the sin which is the cause of my sickness; or it may mean, Restore my life - regarding his life as (as it were) diseased and in danger of extinction. The probability, however, is that he had particular reference to the soul as the word is commonly understood, or as designating himself; heal, or restore me.

For I have sinned against you - Regarding his sin as the cause of his sickness. See the notes at Psalms 38:3-5.