John 21:7 shows the beloved disciple recognizing Jesus—he is the same witness whose testimony is affirmed in 21:24.

John 21:20 again identifies the beloved disciple who leaned on Jesus at supper—the one whose testimony is recorded in 21:24.

John 19:35 also affirms the eyewitness testimony of the Beloved Disciple is true, directly paralleling the claim here about his reliable testimony.

John 13:23 introduces 'the disciple whom Jesus loved,' later identified in 21:24 as the one who testifies and wrote this Gospel.

In John 15:27, Jesus commands the disciples to testify—21:24 shows that command fulfilled by the beloved disciple's written testimony.

John 19:26 identifies the beloved disciple at the cross—the same disciple who later testifies and writes in 21:24.

John 20:2 calls the beloved disciple 'the other disciple' at the empty tomb—connecting to 21:24 as the one who testifies to these events.

3 John 1:12 uses the exact phrase 'our testimony is true', closely matching the claim here that the disciple's testimony is true.

1 John 1:1 emphasizes firsthand eyewitness testimony of Jesus, echoing the same apostolic authority and reliability claimed for the Beloved Disciple.

1 John 1:2 continues the testimony theme, declaring 'we have seen it and testify to it', reinforcing the eyewitness basis of the Gospel.