Cross reference
2 Timothy 4:15
15 of whom you also must beware; for he greatly opposed our words.
2 Timothy 3:8
8 Even as Jannes and Jambres opposed Moses, so do these also oppose the truth; men corrupted in mind, reprobate concerning the faith.
Matthew 10:16-17
16 "Behold, I send you out as sheep in the midst of wolves. Therefore be wise as serpents, and harmless as doves.
17 But beware of men: for they will deliver you up to councils, and in their synagogues they will scourge you.
Philippians 3:2
2 Beware of the dogs, beware of the evil workers, beware of the false circumcision.