'Testify Concerning' in the Bible

And needed not that any should testify concerning man: for he knew what was in man.

If I testify concerning myself, my testimony is not true.

The world cannot hate you; but me it hateth, because I testify concerning it, that its works are evil.

Jesus answered and said to them, Though I testify concerning myself, yet my testimony is true: for I know whence I came, and whither I go; but ye cannot tell whence I come, and whither I go.

Jesus answered them, I told you, and ye believed not: the works that I did in my Father's name, they testify concerning me.

But when the Comforter is come, whom I will send to you from the Father, even the Spirit of truth, who proceedeth from the Father, he will testify concerning me.