Brothers, I write no new commandment to you, but an old commandment which you had from the beginning. The old commandment is the word which you heard from the beginning.
The old commandment is the word which ye have heard from the beginning - Is the “doctrine;” or is what was enjoined. John is often in the habit of putting a truth in a new form or aspect in order to make it emphatic, and to prevent the possibility of misapprehension. See John 1:1-2. The sense here is: “All that I am saying to yea is in fact an old commandment, or one which you have always had. There is nothing new in what I am enjoining on you.”