3 John 1:3
For I rejoiced greatly, when the brethren came and testified of the truth that is in thee, even as thou walkest in the truth.
Cross-reference
3 John 1:4 states no greater joy than hearing children walk in truth — directly reinforcing the rejoicing here over the testimony.
In 3 John 1:2, the author prays for prosperity as your soul prospers; verse 3 then shows truth walking as evidence of that spiritual health.
In 2 Corinthians 7:7, Paul rejoices over Titus's report of the Corinthians' godly response—parallel to John's joy over testimony of walking in truth.
Ephesians 1:15 shows Paul giving thanks upon hearing of believers' faith and love—akin to John rejoicing over testimony of walking in truth.
Colossians 1:8 has Epaphras reporting the Colossians' love—parallel to brothers testifying of Gaius's walking in truth.
1 Thessalonians 3:6-9 describes Paul's joy over Timothy's report of the Thessalonians' faith and love—a strong parallel to John's joy over testimony of walking in truth.
2 John 1:4 uses the identical phrase 'I rejoiced greatly' about walking in truth — a direct parallel to this testimony.
Psalm 26:3 declares 'I walk in your truth'—a direct verbal parallel to the walking in truth that Gaius is commended for.
Psalm 86:11 petitions God to 'walk in your truth'—the same phrase describing Gaius's conduct in 3 John.
1 Corinthians 13:6 says love 'rejoiceth in the truth' — a precise parallel to John rejoicing over Gaius' walk in truth.
1 John 2:24 urges the truth heard from the beginning to abide in you, directly echoing the walking in truth that brings joy here.
Proverbs 20:7 describes the just man walking in integrity — a direct parallel to walking in truth, both emphasizing consistent righteous living.
Proverbs 23:15 shows a father rejoicing over his son's wisdom — mirroring John's joy over Gaius walking in truth.
Philippians 1:27 urges conduct worthy of the gospel — parallel to walking in truth, both concern living out the faith.
Colossians 1:4 mentions hearing of their faith and love — parallel to John hearing testimony of Gaius' truth and walk.
Philemon 1:7 has Paul rejoicing over Philemon's love refreshing saints — mirroring John's joy over Gaius walking in truth.