Isaiah 43:10 - Ellicott's Commentary On The Whole Bible

Ye are my witnesses... — These are collectively addressed as the servant of Jehovah. Their calling and election had not been cancelled, and they might yet fulfil it. They, in that restoration from exile which Isaiah had foretold, should be a living proof of the foresight granted to the prophets, and, therefore, of the foreknowledge of Him who alone could say, “I am He,” to whom past, present, and future were as one; and He, the Eternal, proclaims Himself as being also the only Saviour.