'Testimony is True' in the Bible

There is Another who gives testimony concerning me, and I know that the testimony is true which He offers concerning me.

Jesus answered and said to them, 'And if I testify of myself -- my testimony is true, because I have known whence I came, and whither I go, and ye -- ye have not known whence I come, or whither I go.

and he who hath seen hath testified, and his testimony is true, and that one hath known that true things he speaketh, that ye also may believe.

This is the disciple which testifieth of these things, and wrote these things: and we know that his testimony is true.