Contradiction with Proverbs 19:11
This verse emphasizes the virtue of patience and overlooking insults, which contradicts Job 20:3's emphasis on reacting to perceived insult.
Proverbs 19:11: The discretion of a man deferreth his anger; and [it is] his glory to pass over a transgression. [discretion: or, prudence]
Contradiction with Ecclesiastes 7:21-22
These verses advise against taking to heart everything people say about you, which contradicts the sensitivity to reproach expressed in Job 20:3.
Ecclesiastes 7:21-22: Also take no heed unto all words that are spoken; lest thou hear thy servant curse thee: [take...: Heb. give not thine heart]
Contradiction with Proverbs 15:1
This verse suggests a soft answer turns away wrath, which opposes the idea of responding to insult with indignation as implied in Job 20:3.
Proverbs 15:1: A soft answer turneth away wrath: but grievous words stir up anger.