1 John 2:5-10

but whoever keeps His word, in him the love of God has truly been perfected. By this we know that we are in Him: the one who says he abides in Him ought himself to walk in the same manner as He walked. Beloved, I am not writing a new commandment to you, but an old commandment which you have had from the beginning; the old commandment is the word which you have heard. On the other hand, I am writing a new commandment to you, which is true in Him and in you, because the darkness is passing away and the true Light is already shining. The one who says he is in the Light and yet hates his brother is in the darkness until now. The one who loves his brother abides in the Light and there is no cause for stumbling in him.