Charles H. Spurgeon on Psalms 31:9

Have mercy upon me, O Lord, for I am in trouble. Now, the man of God comes to a particular and minute description of his sorrowful case. He unbosoms his heart, lays bare his wounds, and expresses his inward desolation. This first sentence pithily comprehends all that follows, it is the text for his lamenting discourse. Misery moves mercy —no more reasoning is needed. "Have mercy" is the prayer; the argument is as prevalent as it is plain and personal, "I am in trouble." Mine eye is consumed with grief. Dim and sunken eyes are plain indicators of failing health. Tears draw their salt from our strength, and floods of them are very apt to consume the source from which they spring. God would have us tell him the symptoms of our disease, not for his information, but to show our sense of need. Yea, my soul and my belly (or body). Soul and body are so intimately united, that one cannot decline without the other feeling it. We, in these days, are not strangers to the double sinking which David describes; we have been faint with physical suffering, and distracted with mental distress: when two such seas meet, it is well for us that the Pilot at the helm is at home in the midst of the water floods, and makes storms to become the triumph of his art.