Have mercy upon me, O Lord, for I am in trouble. The psalmist follows up his prayer for mercy by an exposition of his need of mercy. He is in trouble, in sore trouble—"hard pressed," as Hengstenberg translates—distressed both in mind and body.
Mine eye is consumed with grief (comp. Psalms 6:7, where the expression is almost identical). The grief intended is "that produced by provocation or spiteful treatment" (Kay). It causes him to weep so much that his eye is well-nigh "consumed" or "eaten away."
Yea, my soul and my belly. Some explain this as meaning simply "my soul and my body" (Hengstenberg, Alexander, Revised Version); but others regard the "belly" as denoting "the very centre of physical life and of the emotions" (comp.