John Gill Commentary Job 42:6

"Wherefore I abhor [myself], And repent in dust and ashes." — Job 42:6 (ASV)

Wherefore I abhor [myself]
Or all my words, as Aben Ezra; all the indecent expressions he had uttered concerning God; he could not bear to think of them; he loathed them, and himself on account of them: sin is abominable in its own nature, and makes men so; it is loathsome to God, and so it is to all good men when they see it in its proper light; and especially when they have a view of the purity and holiness of God, to which that is so very contrary, and also of his grace and goodness in the forgiveness of it; see (Isaiah 6:3Isaiah 6:5) (Ezekiel 16:63) (20:41) ;

and repent in dust and ashes ;
which was an external ceremony used by mournful and penitent persons; see (Job 2:8) (Jonah 3:6) ; and is expressive of the truth and sincerity of repentance; and never do any more truly mourn for sin and repent of it, are more ashamed of it, or have a more godly sorrow for it, or more ingenuously confess it, and heartily forsake it, than those who with an eye of faith behold God in Christ as a sin forgiving God; or behold their sins through the glass of pardoning grace and mercy; see (Zechariah 12:10) (Luke 7:37Luke 7:47) (1 Timothy 1:13) .