يوحنا الثالثة ١:٣

testified of the truth that is in thee--Greek, "of" (or 'to') thy truth": thy share of that truth in which thou walkest [ALFORD]. even as thou--in contrast to Diotrephes (Jo3 1:9).

I. John receives a good report of Gaius's faith and charity from the brethren. Gaius’s love for the brethren and hospitality to strangers proves his sincerity in the faith. II. Gaius is commended for his hospitality, a virtue extended to strangers and those of different churches. III. John expresses great joy in hearing of Gaius's walk in truth. This reflects the joy of ministers when they see their followers living out their faith. IV. John advises Gaius to continue supporting the brethren by aiding them on their journeys in a godly manner, reflecting Christian generosity. V. The brethren went forth preaching for God's sake, taking nothing from the Gentiles. John emphasizes the need for the church to support such ministers, as they help propagate the truth.

1:3 The traveling teachers (literally brothers) were probably John’s emissaries who traveled from church to church, teaching the Good News and encouraging Christians (see 1:5, 10). • you are living according to the truth: Gaius was faithful to the apostolic gospel of Jesus Christ. The false teachers denied the reality of the incarnation or the sacrificial death of Jesus Christ (cp. 1 Jn 4:1-3).