Written to Gaius, a prominent believing leader in one of the assemblies that John knew about, to commend his hospitality and to encourage him in his Christian life.

III John 

1:10  Wherefore, if I come, I will remember his deeds which he doeth, prating against us with malicious words: and not content therewith, neither doth he himself receive the brethren, and forbiddeth them that would, and casteth them out of the church.
Proverbs 10:10 He that winketh with the eye causeth sorrow: but a prating fool shall fall.

1:11  Beloved, follow not that which is evil, but that which is good. He that doeth good is of God: but he that doeth evil hath not seen God.
Psalm 37:27  Depart from evil, and do good; and dwell for evermore.