'Bear Witness' in the Bible

John was not the Light, but came to testify about the Light.

and He did not need anyone to testify concerning man [and human nature], for He Himself knew what was in man [in their hearts—in the very core of their being].

Jesus answered them, “I have told you so, yet you do not believe. The works that I do in My Father’s name testify concerning Me [they are My credentials and the evidence declaring who I am].

So Pilate said to Him, “Then You are a King?” Jesus answered, “You say [correctly] that I am a King. This is why I was born, and for this I have come into the world, to testify to the truth. Everyone who is of the truth [who is a friend of the truth and belongs to the truth] hears and listens carefully to My voice.”