Contradiction with Matthew 5:44
Psalms 18:49 speaks of praising God among the nations for deliverance from enemies, while Matthew 5:44 instructs to love and pray for 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 Luke 6:27
Psalms 18:49 involves triumph over enemies, whereas Luke 6:27 advises loving and doing good to enemies.
Luke 6:27: But I say unto you which hear, Love your enemies, do good to them which hate you,
Contradiction with Romans 12:14
Psalms 18:49 involves victory over enemies, but Romans 12:14 tells to bless those who persecute you.
Romans 12:14: Bless them which persecute you: bless, and curse not.
Contradiction with Proverbs 24:17
Psalms 18:49 praises God's deliverance from foes, while Proverbs 24:17 warns against rejoicing when enemies fall.
Proverbs 24:17: Rejoice not when thine enemy falleth, and let not thine heart be glad when he stumbleth:
Contradiction with Proverbs 25:21
Psalms 18:49 celebrates overcoming adversaries, contrasted with Proverbs 25:21's guidance to feed a hungry enemy.
Proverbs 25:21: If thine enemy be hungry, give him bread to eat; and if he be thirsty, give him water to drink:
Contradiction with 1 Peter 3:9
Psalms 18:49 relates to deliverance from enemies, whereas 1 Peter 3:9 advises not to repay evil with evil.
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.