Contradiction with Matthew 5:43
Proverbs 3:3 emphasizes keeping mercy and truth, while Matthew 5:43 refers to the old law of loving neighbors and hating enemies, which doesn't advocate mercy towards enemies.
Matthew 5:43: Ye have heard that it hath been said, Thou shalt love thy neighbour, and hate thine enemy.
Contradiction with Luke 14:26
Proverbs 3:3 encourages kindness and truth, but Luke 14:26 suggests hating one's family for the sake of following Jesus, contrasting the permanence of love and mercy.
Luke 14:26: If any [man] come to me, and hate not his father, and mother, and wife, and children, and brethren, and sisters, yea, and his own life also, he cannot be my disciple.
Contradiction with Ephesians 4:31
Proverbs 3:3 instructs to keep mercy and truth bound to you, yet Ephesians 4:31 lists behaviors like bitterness and wrath that contradict storing only love and mercy in one's heart.
Ephesians 4:31: Let all bitterness, and wrath, and anger, and clamour, and evil speaking, be put away from you, with all malice:
Contradiction with Ecclesiastes 3:8
Proverbs 3:3 speaks to mercy as enduring, while Ecclesiastes 3:8 acknowledges a time for hate, conflicting with the constancy of mercy and truth.
Ecclesiastes 3:8: A time to love, and a time to hate; a time of war, and a time of peace.