John 21:24
This is the disciple that bears witness of these things, and wrote these things. That way we know that his witness is true.
John 19:35
He who saw testified and his testimony is true. He knows and he speaks truth that you also may believe.
3 John 1:12
Demetrius has the witness of all men, and of the truth itself. Yes, we also testify and you know our witness is true.
John 15:27
You also bear witness because you have been with me from the beginning.
1 John 1:1-2
We have heard that which was from the beginning. We have also seen it with our own eyes. We looked at it and touched it with our hands. It is the Word of life.
1 John 5:6
This is he who came by water and blood, Jesus Christ. He did not come with the water only, but with the water and with the blood. The Spirit gives witness because it is the truth.