Contradiction with Exodus 20:13
"Thou shalt not kill" contradicts Numbers 25:16, where the call for avenging involves killing.
Exodus 20:13: Thou shalt not kill.
Contradiction with Matthew 5:44
"Love your enemies" contradicts the directive to vex and smite the Midianites given in Numbers 25:16.
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 12:19
"Vengeance is mine; I will repay, saith the Lord" contradicts the instruction for Israel to take vengeance.
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 Proverbs 24:17
"Rejoice not when thine enemy falleth" contradicts the potential rejoicing implied in taking vengeance on Midian.
Proverbs 24:17: Rejoice not when thine enemy falleth, and let not thine heart be glad when he stumbleth:
Contradiction with Ezekiel 33:11
"I have no pleasure in the death of the wicked" contradicts the implied endorsement of killing the Midianites.
Ezekiel 33:11: Say unto them, [As] I live, saith the Lord GOD, I have no pleasure in the death of the wicked; but that the wicked turn from his way and live: turn ye, turn ye from your evil ways; for why will ye die, O house of Israel?