Contradiction with Psalm 112:6
Job 20:9 suggests the wicked will be forgotten, whereas Psalm 112:6 states the righteous will be remembered forever.
Psalm 112:6: Surely he shall not be moved for ever: the righteous shall be in everlasting remembrance.
Contradiction with Ecclesiastes 9:5
Job 20:9 implies the past will be faded and forgotten, but Ecclesiastes 9:5 acknowledges the dead know nothing, yet verse notes their memory is cut off.
Ecclesiastes 9:5: For the living know that they shall die: but the dead know not any thing, neither have they any more a reward; for the memory of them is forgotten.
Contradiction with Isaiah 49:15
Job 20:9 speaks of forgetting, while Isaiah 49:15 emphasizes God's unlikely forgetfulness even beyond a mother's rare forgetting of her child.
Isaiah 49:15: Can a woman forget her sucking child, that she should not have compassion on the son of her womb? yea, they may forget, yet will I not forget thee. [that...: Heb. from having compassion]
Contradiction with Hebrews 6:10
Job 20:9 alludes to being forgotten like a dream, but Hebrews 6:10 assures that God will not forget the work and labor of love shown by believers toward His name.
Hebrews 6:10: For God [is] not unrighteous to forget your work and labour of love, which ye have shewed toward his name, in that ye have ministered to the saints, and do minister.