John 21:24
This is the disciple witnessing concerning these things, and having written the same: and we know that his testimony is true.
John 19:35
And He having seen hath testified, and his testimony is true: and he knows that he speaks the truth, that you also may believe.
3 John 1:12
To Demetrius it has been testified by all, and by the truth itself: and we also testify: and you know that our testimony is true.
John 15:27
but you indeed are witnesses, because you are with me from the beginning.
1 John 1:1-2
That which was from the beginning, which we have heard, which we have seen with our eyes, which we have beheld, and our hands have handled, concerning the Word of the life;
1 John 5:6
He is the one having come through water and blood, Jesus Christ; not by water only, but by water and blood; the Spirit is the one who bears witness, because the Spirit is the truth.