'Beware' in the Bible

Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves.

But beware of men: for they will deliver you up to the councils, and they will scourge you in their synagogues;

Then Jesus said unto them, Take heed and beware of the leaven of the Pharisees and of the Sadducees.

How is it that ye do not understand that I spake it not to you concerning bread, that ye should beware of the leaven of the Pharisees and of the Sadducees?

Then understood they how that he bade them not beware of the leaven of bread, but of the doctrine of the Pharisees and of the Sadducees.