'Testifying' in the Bible

The Pharisees told him, "You're testifying about yourself. Your testimony isn't valid."

Jesus answered them, "Even though I'm testifying about myself, my testimony is valid because I know where I've come from and where I'm going. But you don't know where I come from or where I'm going.

I'm testifying about myself, and the Father who sent me is testifying about me."

This is the disciple who is testifying to these things and has written them down. We know that his testimony is true.