Psalms 102:4

4My heart is smitten, and dried up like grass Here he employs a third similitude, declaring that his heart is withered, and wholly dried up like mown grass. But he intends to express something more than that his heart was withered, and his bones reduced to a state of dryness. His language implies, that as the grass, when it is cut down, can no longer receive juice from the earth, nor retain the life and rigor which it derived from the root, so his heart being, as it were, torn and cut off from its root, was deprived of its natural nourishment. The meaning of the last clause, I have forgotten to eat my bread, is, My sorrow has been so great, that I have neglected my ordinary food. The Jews, it is true, during their captivity in Babylon, did eat their food; and it would have been an evidence of their having fallen into sinful despair, had they starved themselves to death. But what he means to say is, that he was so afflicted with sorrow as to refuse all delights, and to deprive himself even of food and drink. True believers may cease for a time to partake of their ordinary food, when, by voluntary fasting, they humbly beseech God to turn away his wrath, but the prophet does not here speak of that kind of abstinence from bodily sustenance. He speaks of such as is the effect of extreme mental distress, which is accompanied with a loathing of food, and a weariness of all things. In the close of the verse, he adds, that his body was, as it were, consuming or wasting away, so that his bones clave to his skin.