'Be on Your Guard' in the Bible

In the meantime, after so many thousands of the people had gathered that they were stepping on one another, Jesus began speaking first of all to His disciples, “Be continually on your guard against the leaven of the Pharisees [that is, their pervasive, corrupting influence and teaching], which is hypocrisy [producing self-righteousness].

Pay attention and always be on guard [looking out for one another]! If your brother sins and disregards God’s precepts, solemnly warn him; and if he repents and changes, forgive him.

He said, “Be careful and see to it that you are not misled; for many will come in My name [appropriating for themselves the name Messiah which belongs to Me alone], saying, ‘I am He,’ and, ‘The time is near!’ Do not follow them.

“But be on guard, so that your hearts are not weighed down and depressed with the giddiness of debauchery and the nausea of self-indulgence and the worldly worries of life, and then that day [when the Messiah returns] will not come on you suddenly like a trap;