'Be on Your Guard' in the Bible

But be on your guard; I have told you everything in advance.

“Be on guard and stay constantly alert [and pray]; for you do not know when the appointed time will come.

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;

I urge you, brothers and sisters, to keep your eyes on those who cause dissensions and create obstacles or introduce temptations [for others] to commit sin, [acting in ways] contrary to the doctrine which you have learned. Turn away from them.

Therefore, [let me warn you] beloved, knowing these things beforehand, be on your guard so that you are not carried away by the error of unprincipled men [who distort doctrine] and fall from your own steadfastness [of mind, knowledge, truth, and faith],