Albert Barnes' Notes on the Whole Bible - Isaiah 42:5
Thus saith God the Lord - This verse commences a new form of discourse. It is still Yahweh who speaks; but in the previous verses he had spoken of the Messiah in the third person; here he is introduced as speaking to him directly. He introduces the discourse by showing that he is the Creator and Lord of all things. The object of his dwelling on this seems to have been, to show that he had power to sustain the Messiah in the work to which he had called him; and to secure for him respect as... read more
The Pulpit Commentary - Isaiah 42:6
I the Lord have called thee in righteousness . The "Servant of Jehovah" is addressed. God has "called" him; i.e. appointed him to his mediatorial office " in righteousness ," in accordance with the righteous purpose which he has entertained towards his fallen creatures from the beginning of the world. And will give thee for a Covenant of the people (comp. Isaiah 49:8 ). The covenant between God and his people being in Christ, it is quite consistent with Hebrew usage to transfer the... read more