Contradiction with Matthew 5:39
2 Samuel 18:2 describes a battle formation, while Matthew 5:39 advocates for turning the other cheek and not engaging in conflict.
Matthew 5:39: But I say unto you, That ye resist not evil: but whosoever shall smite thee on thy right cheek, turn to him the other also.
Contradiction with Romans 12:19
2 Samuel 18:2 involves preparing for battle and seeking victory, whereas Romans 12:19 advises leaving vengeance to God.
Romans 12:19: Dearly beloved, avenge not yourselves, but [rather] give place unto wrath: for it is written, Vengeance [is] mine; I will repay, saith the Lord.