'Testifies' in the Bible

What he has seen and heard, of that he testifies; and no one receives his witness.

It is another who testifies about me. I know that the testimony which he testifies about me is true.

I am one who testifies about myself, and the Father who sent me testifies about me."

This is the disciple who testifies about these things, and wrote these things. We know that his witness is true.