Contradiction with Psalm 37:25
Job 20:21 suggests wickedness results in empty stomachs, yet Psalm 37:25 states that the righteous are never forsaken nor their children begging bread.
Psalm 37:25: I have been young, and [now] am old; yet have I not seen the righteous forsaken, nor his seed begging bread.
Contradiction with Proverbs 10:3
Job 20:21 implies punishment through want, whereas Proverbs 10:3 claims the Lord does not let the righteous go hungry.
Proverbs 10:3: The LORD will not suffer the soul of the righteous to famish: but he casteth away the substance of the wicked. [the substance...: or, the wicked for their wickedness]
Contradiction with Philippians 4:19
While Job 20:21 implies unfulfilled appetites for the wicked, Philippians 4:19 assures that God will meet all needs according to His riches.
Philippians 4:19: But my God shall supply all your need according to his riches in glory by Christ Jesus.
Contradiction with Matthew 6:31-33
Job 20:21 indicates deprivation for sin, but Matthew 6:31-33 promises that seeking God's kingdom ensures all needs are met.
Matthew 6:31-33: Therefore take no thought, saying, What shall we eat? or, What shall we drink? or, Wherewithal shall we be clothed?
Contradiction with Psalm 34:10
Job 20:21 speaks of unsatisfied desires, yet Psalm 34:10 indicates that those who seek the Lord lack no good thing.
Psalm 34:10: The young lions do lack, and suffer hunger: but they that seek the LORD shall not want any good [thing].
Contradiction with Isaiah 65:13
Job 20:21 points to empty satisfaction, whereas Isaiah 65:13 contrasts the fate of the wicked and servants of God, promising sustenance for the latter.
Isaiah 65:13: Therefore thus saith the Lord GOD, Behold, my servants shall eat, but ye shall be hungry: behold, my servants shall drink, but ye shall be thirsty: behold, my servants shall rejoice, but ye shall be ashamed: