Contradiction with Matthew 15:18
This verse suggests that what comes out of the mouth defiles a person, which could be seen as contradictory if keeping words "in the midst" of one's heart (Proverbs 4:21) leads to negative speech.
Matthew 15:18: But those things which proceed out of the mouth come forth from the heart; and they defile the man.
Contradiction with Proverbs 21:2
This verse implies that every way of a man is right in his own eyes, which may contradict the idea of keeping specific teachings unchallenged in one's heart as proposed in Proverbs 4:21.
Proverbs 21:2: Every way of a man [is] right in his own eyes: but the LORD pondereth the hearts.
Contradiction with Ecclesiastes 1:18
Suggests that increased knowledge brings sorrow, potentially contradicting the idea that keeping wisdom in one's heart is purely beneficial.
Ecclesiastes 1:18: For in much wisdom [is] much grief: and he that increaseth knowledge increaseth sorrow.
Contradiction with Isaiah 55:9
Emphasizes that God's thoughts and ways are higher than human ways, contradicting the idea of holding human instruction as supreme.
Isaiah 55:9: For [as] the heavens are higher than the earth, so are my ways higher than your ways, and my thoughts than your thoughts.
Contradiction with 1 Corinthians 8:1
Says that knowledge puffs up, potentially contradicting the suggestion that retaining teachings (words) is entirely beneficial, without risks of pride.
1 Corinthians 8:1: Now as touching things offered unto idols, we know that we all have knowledge. Knowledge puffeth up, but charity edifieth.
Contradiction with Jeremiah 17:9
Describes the heart as deceitful, which could contradict the emphasis on trusting the heart to retain wisdom.
Jeremiah 17:9: The heart [is] deceitful above all [things], and desperately wicked: who can know it?