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.
Brethren, I write no new commandment unto you but an old commandment: Other translations, based on other manuscripts, have "beloved," agapetoi, rather than "brethren," adelphoi. John is writing to his beloved and cherished brethren in Christ. There are two words in the Greek that are translated "new": neos, new in point of time, and kainos, new as pertains to quality (Wuest, I John 118). The word is kainos here, suggesting the commandment or precept John is writing is not new in quality nor is it a rare and unusual thing to them. Rather, it is "an old commandment." It has been around for a long time. John had just instructed them to walk as Jesus walked, a walk totally motivated by love. The new-old commandment deals with love, a fact he confirms in verses 9-11.