Charles Ellicott Commentary Psalms 102:9

"For I have eaten ashes like bread, And mingled my drink with weeping," — Psalms 102:9 (ASV)

Ashes like bread. —Lamentations 3:16. A figurative expression, like dust shall be the serpent’s meat (Isaiah 65:25). With the last clause compare to Psalms 42:3, tears have been my meat day and night. So too, as an emblem of disappointment, a modern poet:—

“But even while I drank the brook, and ate
The goodly apples, all these things at once
Fell into dust, and I was left alone.”
TENNYSON: Holy Grail.