Charles H. Spurgeon on Psalms 143:7

My spirit faileth. This is David's first reason to move the Lord; he is at the last cast and even giving up the ghost with long waiting for help: from his low condition we may see what is often the condition of God's children, —and the best of God's servants have waited for comfort and the feelings of his Spirit, to the very failing of their own spirit. David, a man after God's own heart, is yet brought low with the faintness and failing of his heart, in waiting for help from God. "In the sweat of thy face shalt thou eat bread" (Ge 3:19); this lies upon the sons of men. But here, not sweat of face only, that were but small; but sighs and fainting of the heart lie upon the sons of God, in seeking and hungering after a taste of God's bread of life, inward comfort, assurance, and joy of the Holy Ghost. Thus the Church was brought to this sick bed ere her comfort came: "For these things I weep; mine eye, mine eye runneth down with water, because the comforter that should relieve my soul is far from me:" La 1:16. The disciples spirits were even failing in the tempest, when Christ slept and seemed to neglect them, as if he cared not though they perished. How should our spirits do other but fail, when our Comforter sleeps, when our only friend seems to be our enemy? Failing of spirit is both a motive which God means to yield unto and to be won by withal; and it is also his opportunity, when he usually helps. It is a strong motive in our prayers to move him, for he is pitiful, and will not let his children utterly fail and perish; he is a pitiful Spirit to failing spirits. "I will not contend (saith the Lord) for ever, neither will I be always wroth; "why? we deserve his wrath should last and take fire for ever against us; yea, but (saith the Lord) this is the reason, "The spirit should fail before me, and the souls which I have made" (Isa 57:16): I love and pity the fainting souls and spirits of men: I will help my children; how can I see my creatures whom I made and do love, to perish for want of my help? David knew the Lord's nature, and that this was speeding argument in prayer, which made him here and elsewhere so often use it. A pitiful father will not see the spirit of his children utterly fail. It is his opportunity; he usually helps when all other helps fail, that we may the more strongly cleave to him, and ground ourselves upon him, as knowing how infirm we are, if he confirm us not. When man's cruse of oil is dry, and fails, and can drop no more, then is God's time to prepare his. Thus helped he the Israelites at the Red Sea, when all man's strength and wisdom was at a stand. He loves to be seen in the mount, in extremities. —Condensed from Thomas Calvert.