This is not a reason of what he last said, Psa_143:2, but an argument to enforce his petition delivered Psa_143:1, and repeated Psa_143:7, &c. For though I am not faultless, if thou shouldst make an exact search into me, yet mine enemies are more culpable and highly unjust, and therefore I hope for thy help against them, from thy justice as well as mercy.
My soul, i.e. my life; for nothing less will satisfy him.
He hath smitten my life down to the ground; he hath beaten me down to the ground, where I lie struggling for life.
He hath made me to dwell in darkness; he hath forced me to have mine abode in dark vaults and caves, where I am out of sight and memory, and in as forlorn and hopeless a condition in the eye of man as those that have lain long rotting in the grave.