Albert Barnes Commentary Job 30:19

"He hath cast me into the mire, And I am become like dust and ashes." — Job 30:19 (ASV)

He has cast me into the mire - That is, God has done it. In this book the name of God is often understood where the speaker seems to avoid it, in order that it may not be needlessly repeated. On the meaning of the expression here, see the notes at Job 9:31.

And I have become like dust and ashes - Either in appearance, or I am regarded as being as worthless as the mire of the streets. Rosenmuller supposes it means, “I am more like a mass of inanimate matter than a living man.”