Contradiction with Matthew 5:44
While Psalms 140:9 desires harm for enemies, Matthew 5:44 teaches to love and pray for one's enemies.
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 Romans 12:14
Psalms 140:9 calls for the harm of enemies, whereas Romans 12:14 instructs believers to bless those who persecute them.
Romans 12:14: Bless them which persecute you: bless, and curse not.
Contradiction with Proverbs 24:17
Psalms 140:9 desires vengeance on enemies, but Proverbs 24:17 advises against rejoicing when your enemy falls.
Proverbs 24:17: Rejoice not when thine enemy falleth, and let not thine heart be glad when he stumbleth:
Contradiction with Romans 12:20
Psalms 140:9 speaks of harm to enemies, while Romans 12:20 encourages feeding and caring for your enemies.
Romans 12:20: Therefore if thine enemy hunger, feed him; if he thirst, give him drink: for in so doing thou shalt heap coals of fire on his head.
Contradiction with 1 Peter 3:9
Unlike Psalms 140:9, which seeks revenge, 1 Peter 3:9 teaches not to repay evil with evil or insult with insult.
1 Peter 3:9: Not rendering evil for evil, or railing for railing: but contrariwise blessing; knowing that ye are thereunto called, that ye should inherit a blessing.
Paradox #1
The contradiction or conflict in Psalms 140:9 could be seen as the desire for harm to come upon one's enemies, which contrasts with other teachings in the Bible that advocate for love, forgiveness, and mercy towards others, including one's enemies.