John Gill emphasizes that the commandment of love is not new but rather an ancient directive rooted in God's eternal nature and will. He explains that this commandment has been known since the beginning, being part of the divine law and taught by Christ and the apostles. The essence of this commandment is to love one another, which reflects the image of God and is foundational to the Christian faith. Gill highlights that this love is reinforced by the teachings of the Gospel, which remind believers of their redemption and the call to love God and each other. Thus, the commandment of love is both timeless and essential for the Christian community.

Ver. 7. Brethren, I write no new commandment unto you,.... Some understand this of faith, which this apostle calls a commandment, 1Jo 3:23; but it rather intends the commandment of love, especially to the brethren, of which the apostle says the same things as here in his second epistle, 1Jo 2:5; and this sense agrees both with what goes before and follows after, and is a considerable branch of the commandments of Christ to be kept, and of walking as he walked; and the word "brethren", prefixed to this account, may direct to, and strengthen this sense, though the Vulgate Latin and Syriac versions read, "beloved"; and so the Alexandrian copy, and others: and this commandment is said to be not a new one, but an old commandment, which ye had from the beginning; it being in its original a part of the eternal law of truth, founded upon the unalterable nature and eternal will of God, who is love itself, and requires it in all his creatures; being what was written on Adam's heart in a state of innocence, and a branch of the divine image stamped upon him; and is what was delivered in the law of Moses, for love to God and men is the sum and substance of that; and was taught by Christ and his apostles from the beginning of the Gospel dispensation; and was what these saints had been acquainted with, and influentially instructed in from their first conversion, being taught of God in regeneration to love one another; so that this was no novel doctrine, no upstart notion, no new law, but of the greatest and most venerable antiquity, and therefore to be regarded in the most respectful manner. The old commandment is the word which ye have heard from the beginning; or this ancient law of love is contained in, and enforced by that word or doctrine which was delivered from the beginning of time; and which these saints had heard of, concerning the seed of the woman's bruising the serpent's head, which includes the work of redemption and salvation by Christ, atonement by his sacrifice, forgiveness of sin through his blood, and justification by his righteousness, than which nothing can more powerfully engage to love God, and Christ, and one another; and which is also strongly encouraged by the word of God and Gospel of Christ, which they had heard, and had a spiritual and saving knowledge of, from the time they were effectually called by the grace of God: the phrase, "from the beginning", is left out in the Alexandrian copy, and others, and in the Vulgate Latin, Syriac, and Ethiopic versions; it is omitted in both clauses of the text in the latter.