'Be on Your Guard' in the Bible

And he warned them, saying, "Look out! Be on your guard against the yeast of the Pharisees and the yeast of Herod!"

But you must be on your guard; they will hand you over to courts and you will be taken into synagogues and beaten, and you will be brought before governors and kings on my account, to testify to them.

But you must be on your guard; I have told you all about it beforehand.