John 17:20 prays for those who will believe 'through their word' — John 19:35 is part of that apostolic testimony leading to belief.

John 20:31 states the Gospel's purpose — that you may believe — directly echoing the 'so that you may believe' in this eyewitness testimony.

John 21:24 confirms that the disciple who wrote these things is the true witness — echoing 19:35's claim.

John 11:15 includes the purpose 'so that you may believe', matching the identical phrase at the end of John 19:35.

John 11:42 shows Jesus praying publicly 'that they may believe' — the same belief-purpose clause used in John 19:35.

John 14:29 says Jesus told things beforehand 'so that when it takes place you may believe', paralleling the belief-purpose in John 19:35.

John 12:17 describes a crowd bearing witness to Jesus raising Lazarus, another instance of testimony in John's Gospel though about a different event.

1 Peter 5:1 calls Peter a witness of Christ's sufferings, directly paralleling the eyewitness testimony of the crucifixion in John 19:35.

1 John 1:1-3 stresses seeing, hearing, and testifying so that others may have fellowship — the same eyewitness purpose as John 19:35.

1 John 5:13 writes to believers for assurance of eternal life, paralleling this verse's purpose of producing belief through testimony.

1 John 5:6 references Jesus coming by water and blood, the same event testified to here, and emphasizes the Spirit's testimony.

3 John 1:12 affirms that 'our testimony is true,' directly paralleling the claim of true testimony in this verse and from the same author.

In Revelation 1:2, John similarly bears witness to what he saw — reinforcing the reliability of his testimony here in the gospel.

Acts 10:39 shows Peter as a witness of Jesus' death, echoing the eyewitness testimony in John 19:35 that leads to belief.

Hebrews 2:3 says the great salvation was attested by those who heard — the same kind of eyewitness testimony John 19:35 provides.