2. Even as thy soul prospereth. He wishes Gaius all good things,
but most of all prosperity of soul.
3. For I rejoiced greatly. Certain brethren had been where Gaius
lived, had enjoyed his hospitality and had spoken well of him to John
on their return.
4. I have no greater joy. That which gave him the greatest joy
was to know that the saints walked in the truth.
My children. The aged John was wont to call the saints his
1 John 2:1, 12, 18, 28;
5-8. Thou doest a faithful work. In his kindness to brethren and
strangers. In those early ages hospitality to the saints sent on
evangelistic missions, and especially to persecuted saints driven from
home, was a very important duty.
6. Which have borne testimony to thy love. These traveling
brethren reported to the Church how Gaius had aided them.
Thou shalt do well. A polite exhortation to continue such
hospitality in the future. The hospitality was wont to be shown not
only by opening the home to these saints, but by helping them on their
7. Because. The persons named were engaged in the work of Christ
(his name's sake).
Taking nothing. They could not ask aid of the Gentiles. The
Greek form does not imply that the Gentiles had tendered presents which
had been rejected (Winer's Greek Grammar of the New Testament,
page 388, note 1). 
9-12. I wrote somewhat unto the church. Of which Gaius was a
member. The letter referred to is not extant.
But Diotrephes. This man is not elsewhere named. He was
evidently an ambitious and unscrupulous church official, who rebelled
against the apostle's authority
(receiveth us not), and who refused to heed the letter. The
letter may have been sent by those whom Gaius entertained.
10. Wherefore, if I come. It may be necessary for him to come.
If he does, he will arraign Diotrephes for his deeds.
Prating against us. Excusing himself by maligning John.
Neither doth he himself receive the brethren. The messengers
He forbiddeth. Seeks to prevent any of the church from hearing
or extending hospitality to these messengers.
Casting them out of the church. Seeks to have them denied
11. Follow not that which is evil. The wicked example of one
12. Demetrius hath the witness of all. Of this Demetrius we know
nothing more. Perhaps he was a member of the same church as Diotrephes,
whose example is contrasted.