Hear, O Jehovah! In this clause the Psalmist softens and corrects his former complaint; for it would have been absurd to expostulate with God like one who despaired of safety, and to leave off in this fretful temper. Having asked, therefore, with tears, what profit God would derive from his death, he encourages himself to a more unconstrained manner of prayer, and, conceiving new hope, calls upon God for mercy and help. He puts God's favor, however, in the first place, from whom alone he could expect the help which he implored.

Hear, O Lord, and have mercy upon me, - etc. This, too, is the prayer which he uttered in the calamities adverted to in Psalm 30:7. It is a cry for mercy founded on the idea referred to in Psalm 30:9.

Hear, O Lord, and have mercy upon me,.... By lifting up the light of his countenance again upon him; by manifesting and applying his pardoning grace to him, and by delivering him out of all his afflictions;
Lord, be thou my helper; in this time of trouble; for he knew that vain was the help of man; and he was entirely in the right to betake himself to the Lord, who was able to help him, when none else could.