2 John 1:4-11 ESV
I rejoiced greatly to find some of your children walking in the truth, just as we were commanded by the Father. And now I ask you, dear lady—not as though I were writing you a new commandment, but the one we have had from the beginning—that we love one another. And this is love, that we walk according to his commandments; this is the commandment, just as you have heard from the beginning, so that you should walk in it. For many deceivers have gone out into the world, those who do not confess the coming of Jesus Christ in the flesh. Such a one is the deceiver and the antichrist. Watch yourselves, so that you may not lose what we have worked for, but may win a full reward. Everyone who goes on ahead and does not abide in the teaching of Christ, does not have God. Whoever abides in the teaching has both the Father and the Son. If anyone comes to you and does not bring this teaching, do not receive him into your house or give him any greeting, for whoever greets him takes part in his wicked works.
ESV: English Standard Version 2016