John 19:33-35, 21:24; 1 John 4:14; Revelations 1:1-2

But when they came to Jesus and saw that he was already dead, they did not break his legs. But one of the soldiers pierced his side with a spear, and at once there came out blood and water. He who saw it has borne witness - his testimony is true, and he knows that he is telling the truth - that you also may believe.

This is the disciple who is bearing witness about these things, and who has written these things, and we know that his testimony is true.

And we have seen and testify that the Father has sent his Son to be the Savior of the world.

The revelation of Jesus Christ, which God gave him to show to his servants the things that must soon take place. He made it known by sending his angel to his servant John, who bore witness to the word of God and to the testimony of Jesus Christ, even to all that he saw. (ESV)