John 5:31

"If I bear witness of myself, my witness is not true."

Cross References (ranked by relevance)

Let another man praise thee, and not thine own mouth; a stranger, and not thine own lips.

Jesus answered, If I honour myself, my honour is nothing: it is my Father that honoureth me; of whom ye say, that he is your God:

Revelation 3:14

And unto the angel of the church of the Laodiceans write; These things saith the Amen, the faithful and true witness, the beginning of the creation of God;