Psalms 102:9 - Matthew Poole's English Annotations on the Holy Bible

For; so this verse gives a reason either of his great sadness, expressed Psalms 102:6,7, or why they swore by him in the sense last given. Or, surely, as this particle is oft used. Or, therefore, because of those bitter reproaches last mentioned. I have eaten ashes like bread: the sense is, Dust and ashes are as constant and familiar to me as the eating of my bread; I cover my head with them; I sit, yea, lie down and roll myself in them, as mourners oft did, 2 Samuel 13:19 Job 2:8,12 Job 16:15 Isaiah 47:1 Micah 1:10; by which means the ashes might easily be mingled with their meat, as tears were with their drink in the next clause. Mingled my drink with weeping; he alludes to the custom of mingling their wine with water.