Verse 1-2
Psalms 143:1-2. In thy faithfulness — According to thy true and faithful promises, made to the penitent who apply to thee for pardon and aid; answer me — Grant my earnest request; and in thy righteousness — Whereby thou art inclined and engaged by promise to favour righteous persons and just causes. Or, the word, here rendered righteousness, may signify mercy, as it often does; for “God’s promises are only conditional, and our sins and frailties are so many, that we have always need of God’s mercy to make us capable of being reputed of the number of those who have complied with the conditions annexed to the promises.” And enter not into judgment, &c. — As if he had said, When I appeal to thy righteousness, I do not do it under an idea that I can justify myself upon a strict trial at the tribunal of thy justice; for I know, if thou shouldst rigorously examine all the tempers and affections of my heart, and actions of my life, I should certainly be condemned by thee to wrath and punishment; for in thy sight shall no man living be justified — That is, according to thy holy and righteous law, and upon the terms of strict justice, without thy indulgence and infinite mercy. Observe well, reader, no man, in order to his justification before God, can plead innocence or his own righteousness; either that he has not sinned, or that he does not deserve to die for his sins; nor must he suppose that he has any satisfaction of his own to offer. Whoever expects to be justified, must look for that inestimable blessing, followed by peace with God, adoption into his family, and a title to life eternal, as an act of pure grace, a free and undeserved gift from the divine mercy, to be conferred upon the penitent and believing, through the redemption which is in Christ Jesus: see Romans 3:9-28.

Verse 3-4
Psalms 143:3-4. For the enemy hath persecuted my soul — This is not a reason of what he said last, Psalms 143:2, but an argument to enforce his petition, delivered Psalms 143:1, and repeated Psalms 143:7. He hath smitten my life down to the ground — He hath beaten me down to the earth, where I lie struggling for life. He hath made me to dwell in darkness — Not only in dark caves, but under dark apprehensions, and clouds of trouble and distress, out of which I see no way of deliverance, except from thy power and mercy; as those that have been long dead — In as hopeless a condition in the eye of man, as those that have lain long in the grave. Therefore is my spirit overwhelmed — See on Psalms 142:3. My heart within me is desolate — Deprived of all hope and comfort, except from thee; or, is astonished, as ישׁתומם may be properly rendered.

Verse 5-6
Psalms 143:5-6. I remember the days of old — That is, but still, upon a more calm reflection, I consider what thou hast done for thy servants in former times, and likewise what thou hast done for me during the persecutions of Saul, and long before that time, in my younger days, when thou didst deliver me from the greatest danger: see 1 Samuel 17:34, &c. I stretch forth my hands, &c. — I pray to thee fervently. My soul thirsteth after thee — After thy favour and help; as a thirsty land — For rain.

Verses 7-9
Psalms 143:7-9. Hear me speedily — Defer no longer; for my spirit faileth — I am just ready to faint. Hide not thy face — Be not angry with me; do not turn from me as one displeased with me, nor deprive me of the light of thy countenance: if I have thy favour let me know that I have it; lest I be like unto them that go down into the pit — That are dead and buried, of whom there is no hope; or, lest I be discouraged, dejected, and disconsolate. Cause me to hear thy loving-kindness in the morning — Early, seasonable, and speedily, as this phrase is taken Psalms 90:14. Cause me to know the way wherein I should walk — So as to please thee and to secure myself; I flee unto thee to hide me — Without whose care these caves, and rocks, and human helps can give me no protection.

Verses 10-12
Psalms 143:10; Psalms 143:12. Teach me to do thy will — To continue in faithful obedience to thee, notwithstanding all temptations to the contrary. Thy Spirit is good, lead me, &c. — Or rather, as it is exactly in the Hebrew, and as many, both ancient and modern translators, render the clause, Let thy good Spirit lead me. Leave me not to mine own blind or vain mind, or corrupt affections; neither give me up to the evil spirit, as thou didst Saul, but conduct me in all my ways by thy good, or gracious, and holy Spirit; into the land of uprightness — In a straight, plain, and level way, that I may not stumble nor fall either into sin or mischief. This is opposed to the crooked and rugged ways in which sinners are said to walk, Psalms 125:5; Proverbs 2:15. And of thy mercy cut off mine enemies, and destroy all them that afflict my soul — That is, out of thy mercy to me, whose life they seek.