Isaiah 44:20
He feedeth on ashes: a deceived heart hath turned him aside, that he cannot deliver his soul, nor say, Is there not a lie in my right hand? He feedeth on ashes: a deceived heart hath turned him aside, that he cannot deliver his soul, nor say, Is there not a lie in my right hand?
The verse stands within Isaiah's contrast between handmade idols and the true God as Maker of heaven and earth, for the works of God make plain that idols are human creations that cannot take the Creator's place. In that setting it reveals God's purpose for His people by directing them to God's wisdom rather than the wisdom of finite people. It warns them against turning from God to finite human wisdom.
A heart deceived by worthless worship and by evil is turned aside, so that the person feeds on ashes that cannot satisfy. Deceived and turned aside, he gropes in spiritual blindness. He cannot deliver his soul, nor can he recognize the lie he holds in his hand. Trust in idols cannot deliver even when rescue from danger is sought, as was seen when people in Italy carried images of saints and pleaded with them for deliverance from cholera, a superstition encouraged by priests.
Long feeding on ashes describes people among the heathen nations whose souls remain unsatisfied because they have long lacked the light of truth. Yet those who are honest in heart and desire light and a better way can be reached by divine grace. The same image applies to transgression in general, whose promised rewards turn to ashes that disappoint and leave the person desolate. The way back is to return to God, who has redeemed the sinner and invites him to come to Him.