1 John 2:4-9

He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him. But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him. He that saith he abideth in him ought himself also so to walk, even as he walked. Brethren, I write no new commandment unto you, but an old commandment which ye had from the beginning. The old commandment is the word which ye have heard from the beginning. Again, a new commandment I write unto you, which thing is true in him and in you: because the darkness is past, and the true light now shineth. He that saith he is in the light, and hateth his brother, is in darkness even until now.