3 John 1:3 provides the specific testimony of Gaius walking in truth that sparks the joy restated in verse 4.

In 1 Kings 3:6, David is described as walking in faithfulness—an OT example of the same 'walking in truth' that brings joy here.

Galatians 4:19 shows Paul laboring for his little children until Christ is formed, echoing John's joy in his children walking in truth.

In Galatians 2:14, Paul rebukes Peter for not acting in line with the gospel truth—showing the opposite of walking in truth that brings joy.

1 Corinthians 4:15 describes Paul as a father who begot the Corinthians in Christ, paralleling John's parental joy in his spiritual children.

Isaiah 38:3 records Hezekiah's same prayer of walking faithfully, providing another witness to the pattern of faithful conduct.

Proverbs 23:24 says a father rejoices in a wise righteous child, matching John's joy that his children walk in truth.

1 Kings 2:4 conditions the throne on sons walking before God in truth — the same phrase 'walk in truth' that brings John his greatest joy.

Hezekiah's prayer in 2 Kings 20:3 echoes David's faithful walk, showing another OT figure who walked before God with integrity.

Psalm 26:1-3 portrays a blameless life lived in reliance on God's faithfulness—mirroring the walk in truth celebrated here.

Proverbs 23:15 directly echoes the parent's joy when a child's heart is wise — identical theme of rejoicing over a child's faithful walk.

2 John 1:4 repeats almost verbatim the joy of finding children walking in truth—identical theme and wording.

Philippians 2:19 has Paul hoping to be cheered by news of them — direct parallel to John's joy from hearing of his children's walk.

Philippians 1:27 expresses Paul's desire to hear of believers standing firm in faith — directly parallels John's joy from hearing of faithful conduct.

Psalm 26:3 continues the theme of living in reliance on God's faithfulness—a specific instance of the walk in truth.

Proverbs 17:21 contrasts a foolish child who brings grief—the opposite of the joyful report of children walking in truth here.

John 12:36 speaks of becoming 'children of light'—a parallel to 'children walking in truth,' both describing identity and conduct.

John 12:35 uses the same 'walk' metaphor but for walking in light—a parallel call to conduct consistent with divine revelation.

Psalm 86:11 is a prayer to be taught God's way and rely on his faithfulness—the desired posture that leads to walking in truth.

Philemon 1:10 calls Onesimus Paul's son begotten in chains, a specific instance of the spiritual parent‑child relationship John celebrates.

Acts 11:23 shows Barnabas glad when he saw God's grace and exhorted steadfastness — joy from others' faithful response to truth.

Colossians 1:4 mentions hearing of the Colossians' faith and love — a similar joy from reports of spiritual progress, implied in context.

Proverbs 20:7 promises blessing on children of the righteous who walk in integrity — a parallel to John's joy from children walking in truth.

Romans 1:12 describes mutual encouragement from each other's faith — a shared joy in faith, though more reciprocal than John's parental joy.

1 Corinthians 16:18 mentions refreshment of spirit from faithful servants — parallel to John's joy from those walking in truth.

Philippians 2:2 links Paul's joy to believers being of one mind and love — joy from their spiritual unity, a narrower parallel.