'Witness' in the Bible

(and the life has been manifested, and we have seen, and bear witness, and report to you the eternal life, which was with the Father, and has been manifested to us:)

This is he that came by water and blood, Jesus the Christ; not by water only, but by water and blood. And it is the Spirit that bears witness, for the Spirit is the truth.

For they that bear witness are three:

If we receive the witness of men, the witness of God is greater. For this is the witness of God which he has witnessed concerning his Son.

He that believes on the Son of God has the witness in himself; he that does not believe God has made him a liar, because he has not believed in the witness which God has witnessed concerning his Son.

And this is the witness, that God has given to us eternal life; and this life is in his Son.