Contradiction with Matthew 5:44
1 Samuel 22:12 is about King Saul speaking to someone he feels betrayed him, while Matthew 5:44 teaches to love your enemies and bless those who curse you.
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 Exodus 20:13
1 Samuel 22:12 involves an inquiry preceding violence, whereas Exodus 20:13 prohibits murder, highlighting a contradiction in responses to perceived betrayal.
Exodus 20:13: Thou shalt not kill.
Contradiction with Romans 12:19
In 1 Samuel 22:12, Saul is preparing to enact vengeance, whereas Romans 12:19 advises against taking revenge, emphasizing leaving it to God's wrath.
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.