Contradiction with Proverbs 27:2
This verse advises letting others praise you and not doing so yourself, whereas 2 Samuel 19:25 involves self-justification.
Proverbs 27:2: Let another man praise thee, and not thine own mouth; a stranger, and not thine own lips.
Contradiction with James 4:10
Encourages humility under the Lord, while 2 Samuel 19:25 might imply self-exaltation.
James 4:10: Humble yourselves in the sight of the Lord, and he shall lift you up.
Contradiction with 2 Corinthians 10:18
Stresses that commendation from the Lord; not oneself, is what matters, in contrast to self-defense in 2 Samuel 19:25.
2 Corinthians 10:18: For not he that commendeth himself is approved, but whom the Lord commendeth.
Contradiction with Matthew 7:1
Advises against judgment, yet 2 Samuel 19:25 involves explaining one's actions.
Matthew 7:1: Judge not, that ye be not judged.
Contradiction with Galatians 6:3
Warns of self-deception and thinking oneself to be something when they are not, unlike the self-defense in 2 Samuel 19:25.
Galatians 6:3: For if a man think himself to be something, when he is nothing, he deceiveth himself.