John Calvin Commentary Psalms 30:10

"Hear, O Jehovah, and have mercy upon me: Jehovah, be thou my helper." — Psalms 30:10 (ASV)

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.