10 distinct Greek words appear in this verse.

• Love
• Obedience and Disobedience

12 passages from patristic writers, Reformers, and church catechisms citing this verse.

• 1John 2:7 — 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.
• 1John 2:8 — 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.
• 1John 3:11 — For this is the message that ye heard from the beginning, that we should love one another.
• 1John 3:11 — For this is the message that ye heard from the beginning, that we should love one another.
• 1John 3:14 — We know that we have passed from death unto life, because we love the brethren. He that loveth not his brother abideth in death.
• 1John 3:16 — Hereby perceive we the love of God, because he laid down his life for us: and we ought to lay down our lives for the brethren.
• 1John 3:23 — And this is his commandment, That we should believe on the name of his Son Jesus Christ, and love one another, as he gave us commandment.
• 1John 3:23 — And this is his commandment, That we should believe on the name of his Son Jesus Christ, and love one another, as he gave us commandment.
• 1John 4:11 — Beloved, if God so loved us, we ought also to love one another.
• 1John 4:21 — And this commandment have we from him, That he who loveth God love his brother also.
• 1John 4:21 — And this commandment have we from him, That he who loveth God love his brother also.
• 1Pet 1:22 — Seeing ye have purified your souls in obeying the truth through the Spirit unto unfeigned love of the brethren, see that ye love one another with a pure heart fervently:
• 1Pet 3:8 — Finally, be ye all of one mind, having compassion one of another, love as brethren, be pitiful, be courteous:
• 1Pet 4:8 — And above all things have fervent charity among yourselves: for charity shall cover the multitude of sins.
• 1Thess 3:12 — And the Lord make you to increase and abound in love one toward another, and toward all men, even as we do toward you:
• 1Thess 4:9 — But as touching brotherly love ye need not that I write unto you: for ye yourselves are taught of God to love one another.
• 1Thess 4:9 — But as touching brotherly love ye need not that I write unto you: for ye yourselves are taught of God to love one another.
• 2John 1:5 — And now I beseech thee, lady, not as though I wrote a new commandment unto thee, but that which we had from the beginning, that we love one another.
• 2Thess 1:3 — We are bound to thank God always for you, brethren, as it is meet, because that your faith groweth exceedingly, and the charity of every one of you all toward each other aboundeth;
• Col 3:14 — And above all these things put on charity, which is the bond of perfectness.
• Eph 5:2 — And walk in love, as Christ also hath loved us, and hath given himself for us an offering and a sacrifice to God for a sweetsmelling savour.
• Eph 5:2 — And walk in love, as Christ also hath loved us, and hath given himself for us an offering and a sacrifice to God for a sweetsmelling savour.
• Gal 6:2 — Bear ye one another’s burdens, and so fulfil the law of Christ.
• John 13:34 — A new commandment I give unto you, That ye love one another; as I have loved you, that ye also love one another.
• John 13:34 — A new commandment I give unto you, That ye love one another; as I have loved you, that ye also love one another.
• John 14:5 — Thomas saith unto him, Lord, we know not whither thou goest; and how can we know the way?
• John 15:17 — These things I command you, that ye love one another.
• Rom 12:10 — Be kindly affectioned one to another with brotherly love; in honour preferring one another;