Seeing you have purified your souls in your obedience to the truth through the Spirit in sincere brotherly affection, love one another from the heart fervently:
[see that ye] love one another with a pure heart fervently: this is Christ's new commandment, and the evidence of regeneration; a distinguishing badge of Christianity, and without which all profession of religion is a vain and empty thing: this should he mutual and cordial; should proceed from the heart, and from an heart sprinkled from an evil conscience; and should be with warmth and fervency, and not with coldness and indifference; though the word here used, εκτενως, may not only design the intenseness of it, but the extensiveness of it also; as that it should reach to all the saints, the poor as well as the rich, and the lesser as well as the greater and more knowing believers; and likewise may denote the continuance of it; it ought to be continually exercised, and to last always; and so the Arabic version renders it, "with a perpetual love".