Ye are my witnesses, saith the Lord,.... The people of Israel, who could testify that the Lord had foretold their affliction in Egypt, their coming from thence, and settling in the land of Canaan, many hundreds of years before they came to pass, and which were exactly fulfilled; and so the apostles of Christ, and ministers of the word, and all Christian people in all nations, are witnesses of the prophecies concerning Christ, his birth, miracles, obedience, sufferings, death, resurrection, ascension to heaven, and session at the right hand of God, all which are exactly accomplished, Ac 1:8:and my servant whom I have chosen; meaning either the Prophet Isaiah, or the prophets in general; or rather the Messiah.
So the Targum,"and my servant the Messiah, in whom I am well pleased;''and who is called the faithful witness, Re 1:5, and to whom the characters of a servant, and the Lord's chosen, well agree, Isa 42:1:that ye may know and believe me, and understand that I am he; by which testimonies and evident proofs of deity, from the prediction of future events, and the accomplishment of them, you may have a competent knowledge, a firm persuasion, and a clear perception of this important truth, that the God of Israel, and of all true Christians, is the one only Lord God:before me there was no God formed, neither shall there be after me; intimating that idols were formed by the hands of men, and yet none of these were formed before him, and therefore could make no pretensions to deity, or to an equality with him; nor should any be formed afterwards, that could be put in competition with him.