'You are My Witnesses' in the Bible

You are My witnesses, says Jehovah, and My servant whom I have chosen; that you may know and believe Me, and understand that I am He. Before Me no God was formed, nor shall there be after Me.

I have declared, and have saved, and I have shown, when there was no strange god among you; therefore you are My witnesses, says Jehovah, that I am God.

Fear not, nor be afraid; have I not told you and made you hear since then? So you are My witnesses. Is there a God besides Me? Yea, there is none. I have not known a Rock.