Contradiction with Proverbs 11:14
While 2 Samuel 17:7 suggests the advice given was wrong, Proverbs 11:14 emphasizes that in the multitude of counselors there is safety.
Proverbs 11:14: Where no counsel [is], the people fall: but in the multitude of counsellors [there is] safety.
Contradiction with James 1:5
2 Samuel 17:7 implies a lack of wisdom in Ahithophel's advice, whereas James 1:5 states that God gives wisdom to all who ask.
James 1:5: If any of you lack wisdom, let him ask of God, that giveth to all [men] liberally, and upbraideth not; and it shall be given him.
Contradiction with Matthew 10:16
In 2 Samuel 17:7, the advice given involves deception, whereas Matthew 10:16 advises being wise and harmless.
Matthew 10:16: Behold, I send you forth as sheep in the midst of wolves: be ye therefore wise as serpents, and harmless as doves. [harmless: or, simple]