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.