Albert Barnes Commentary Psalms 143:1

"Hear my prayer, O Jehovah; give ear to my supplications: In thy faithfulness answer me, [and] in thy righteousness." — Psalms 143:1 (ASV)

Hear my prayer, O Lord, give ear... - See Psalms 4:1, note; Psalms 5:1, note.

In thy faithfulness answer me - That is, Show your faithfulness to your promises. God had made gracious promises to David , and he now pleads that God would remember those promises and accomplish on his behalf what He had said He would. God has also made gracious promises to His people, and they may always plead those promises as a reason why they should be heard and why their prayers should be answered.

And in thy righteousness - Compare Psalms 31:1. In your disposition to do right; to vindicate a righteous cause; to interpose when wrong is done. We, though sinners before God, may feel that our cause is a just one toward our fellow men, and, when wronged, we may ask God to interpose, as a righteous God, on our behalf. We cannot, however, ask Him to save us on the ground of our righteousness toward Him, for we have no such righteousness. See Psalms 143:2.