'Witness' in the Bible

I call on God as a witness, on my life, that it was to spare you that I did not come to Corinth.

Now he who has made us for this very thing is God, who has given us the Spirit as a witness of what is to come.

For according to their power, I bear witness, and beyond their power, they were willing of their own accord,

and not only so, but is also chosen by the assemblies as our fellow-traveller with this grace, ministered by us to the glory of the Lord himself, and a witness of our readiness;

The God and Father of our Lord Jesus Christ, to whom be praise for ever, is witness that the things which I say are true.