Fear ye not, neither be afraid: have not I told thee from that time, and have declared it? ye are even my witnesses. Is there a God beside me? yea, there is no God; I know not any.
Neither be afraid - literally, be astounded or distracted with fear (from a root yarah).
Have not I told thee from that time - namely, from the time that "I appointed the ancient people" (Isaiah 44:7). From the time of Abraham's call, his family were the depositaries of the predictions, of the Redeemer; whereas the promise of Cyrus was not heard of until Isaiah's time; therefore, the event to the prediction and accomplishment of which God appeals in proof of His sole Godhead is the redemption of man by a descendant of Abraham, in whose person "the ancient people" was first formally "appointed." The deliverance of the Jews by Cyrus is mentioned afterward only as an earnest of that greater mercy (Horsley).
Is there a God besides me? yea, (there is) no God - literally, 'no rock' (Hebrew, tsur, 'rock') (Deuteronomy 32:4);
i.e., a stronghold to take refuge in, and a solid foundation to build on.