1 John 2:5-8

but whoever keeps his word, in him truly the love of God is perfected. By this we may know that we are in him: whoever says he abides in him ought to walk in the same way in which he walked. Beloved, I am writing you no new commandment, but an old commandment that you had from the beginning. The old commandment is the word that you have heard. At the same time, it is a new commandment that I am writing to you, which is true in him and in you, because the darkness is passing away and the true light is already shining.