Contradiction with Matthew 5:44
This verse advises to love your enemies and pray for those who persecute you, which contrasts with the mourning and implicit enmity shown in 2 Samuel 3:32.
Matthew 5:44: But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you;
Contradiction with Proverbs 24:17
This verse instructs not to rejoice when an enemy falls, whereas 2 Samuel 3:32 depicts sorrow for an enemy's death.
Proverbs 24:17: Rejoice not when thine enemy falleth, and let not thine heart be glad when he stumbleth:
Contradiction with Romans 12:19
Advises against taking personal vengeance, which contrasts with the mourning suggesting a personal vendetta in the context of 2 Samuel 3:32.
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.
Contradiction with Ephesians 4:31
Calls to put away all bitterness, which contradicts the display of grief and implied bitterness in 2 Samuel 3:32.
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 Proverbs 20:22
Encourages waiting on the Lord for justice, opposing the display of vengeance through mourning in 2 Samuel 3:32.
Proverbs 20:22: Say not thou, I will recompense evil; [but] wait on the LORD, and he shall save thee.