Jamieson, Fausset and Brown on Job 42:3

3. I am the man! Job in God's own words (Job 38:2) expresses his deep and humble penitence. God's word concerning our guilt should be engraven on our hearts and form the groundwork of our confession. Most men in confessing sin palliate rather than confess. Job in omitting "by words" (Job 38:2), goes even further than God's accusation. Not merely my words, but my whole thoughts and ways were "without knowledge."

too wonderful--I rashly denied that Thou hast any fixed plan in governing human affairs, merely because Thy plan was "too wonderful" for my comprehension.