The Great Commandment - Love
John 15:12–13 (ESV) … “This is my commandment, that you love one another as I have loved you. Greater love has no one than this, that someone lay down his life for his friends.”
Not only do the friends of Jesus remain in his love; they must also obey his commands. These three verses represent a power-packed passage of the New Testament.
John never forgot these words. They appear in various forms throughout his three epistles, particularly the first. John 15:13 is one of the most dramatic verses of the New Testament: Greater love has no one than this, that he lay down his life for his friends. But we sometimes forget verse 14 that links friendship with obedience to the command to love. Sometimes Christians get so busy figuring out how they should be loving God that they forget to love one another. In fact, a constant and genuine love for one another would be one way to show love for God. We do well at this point in the Gospel of John to remember Romans 5:8: “But God demonstrates his own love for us in this: While we were still sinners, Christ died for us.”
When we study the imperatives of the four Gospels, we see that Jesus left many commands for his disciples and for us. But this one seems to take precedence over all the others. The central command has nothing to do with doctrine, church size, or the order of worship. It could not be simpler to understand or more difficult to carry out: Love each other as I have loved you.
 Gangel, K. O. (2000). John (Vol. 4, p. 285). Nashville, TN: Broadman & Holman Publishers.