'Testimony' in the Bible
Jesus Christ is He who came with water and blood; not with the water only, but with the water and with the blood. And it is the Spirit who gives testimony-- because the Spirit is the Truth.
For there are three that give testimony-- the Spirit, the water, and the blood;
the Spirit and the water and the blood; and these three are in agreement [their testimony is perfectly consistent].
If we accept the testimony of men, God’s testimony is greater, because it is God’s testimony that He has given about His Son.
(The one who believes in the Son of God has this testimony within him. The one who does not believe God has made Him a liar, because he has not believed in the testimony God has given about His Son.)
And this is the testimony: God has given us eternal life, and this life is in His Son.